The latest update to Apple's OS X, Snow Leopard, is finally unleashed upon the world. At £25 you might not need to question whether there is any reason to wait before you rush out to buy it.

As the name suggests, Snow Leopard builds on a foundation already laid down by Leopard. It looks the same and it works the same. Everything is in the same place, so it feels less like a new operating system and more like a major tweak, which is exactly what it is.

The operating system is made up of over 1000 "projects", Apple tells us, and 90% of these projects have been tweaked in some way. Some you'll never notice and as many of the changes are behind the scenes, visually, you'll find little difference, even if you notice the performance improvements right away.

It's a lighter install, and Apple boast you'll save around 7GB through the install: we got more than 10GB back. It also only takes 5GB of space to install, after which you'll find you have the extra space: it's a nice bonus and feels like something for nothing.

The installation process, it is claimed, is 50% faster. We ran the installation on a 2008 unibody MacBook but took the time to test a neat feature – power failure protection. The idea is to make sure that nothing goes wrong if you suddenly lose power during the installation process. It seemed to work, resuming where it had left off without a hitch, but did skew timing of the installation…

If you're used to installing a new OS and then having to rebuild your file system and shortcuts, you might be disappointed here. We found everything where we left it. The wallpaper was the same, the stacks where the same, all the Dock icons where the same. The only thing we noticed was that out Google Calendars showed no appointments in iCal. A quick refresh brought them all back, so overall, not a problem.

So where are the changes and how will they affect your daily use of your Mac?

Finder has been completely rebuilt but it still looks the same. In reality it is faster to open (as everything seems to be) and faster to browse files and folders with a noticeable snap to things. Some other features handled by Finder have also been tightened-up.

Files transfers have been improved, so when you cancel a file transfer by clicking on the cross, it actually does stop almost instantly. The same speed boost applies to ejecting drives, which happens much faster than before. If you regularly connect USB drives, you'll probably be familiar with the message telling you it is still in use, but in Snow Leopard it will tell you which application is using it (or thinks it is using it).

Apple has also increased the usefulness of icons/thumbnails in Finder. This might sound like a gimmick at first, but again, it's a convenient move and potentially changes the number of files you have to open, or use quick view on.

You can increase icon sizes (or reduce them) with a slider in the bottom right-hand corner of Finder windows, or using a pinch zoom on the trackpad. The great thing is you can have different sizes in different windows, so you might want photos and videos larger, and documents smaller, for example.

At the moment not all icons seem to work so well, we found some portrait image files that couldn't handle the magnification, and some application icons don't like going big - Google Chrome looks gorgeous, Handbrake looks awful.

Previously you could always hit the space bar and have a quick view of files, but now you can do that within the icon, depending on file type.

Pages and PDF files get the benefit of you being able to click through multiple pages, so if you refer to a lot of documents, you might find it a really fast way of finding a particular table or graphic in a report. You can then hit space bar and your quick view comes up on that page, so you can read all the text if you need it, which is very smart, but a bona fide Preview still opens at the start of the document.

Not all files benefit from this unfortunately, and you can't do the same thing to Word or OpenOffice files, which does let the side down a little bit and reflects something that is abundantly obvious in Snow Leopard: third party applications don't get all the same benefits, yet.

One thing that really impresses, however, is being able to have a quick view of video files straight from the icon. We tried it across a range of file types with no problems, except the lacking MKV support. If you work with a lot of video clips, this could save you loads of time.

Exposé has also been cleaned up. The previous version was cool, but rather random, with different windows slotted into pretty much any space. Now there is greater alignment, so things look neater. You can also arrange your windows in Exposé by using Cmd 1 or 2 to arrange by type or by name respectively.

The Exposé refinements continue with Dock integration too, with new features that are really practical. From Exposé, click a Dock icon and you'll then be shown only the windows from that application in Exposé. You can click along the icons reviewing associated windows until you find what you want. It's a neat trick and one that we've already used a lot, dragging and dropping files via Exposé.

Stacks have been tidied up too and we like the fact you now have a scroll bar, so if you've a load of files in your Downloads stack, for example, you can scroll down and find them easily (which should encourage you to file or delete some of them ... ahem).

Preview has been sharpened-up, with Apple boasting a 2.3x speed improvement on JPEG viewing and 1.4x speed boost on PDFs. We can't say we really notice these speed improvements until you go to preview a whole folder full, where it's really impressive.

The other application that has noticeably changed is QuickTime. Now in its new guise as QuickTime X, it is a cleaner, minimalist (visually) version of the video player, with a couple of new tricks added in. Firstly you can easily trim clips in the same way you can in iPhoto or on the iPhone and share them in iTunes, MobileMe or YouTube straight from QuickTime itself. The YouTube uploader also sticks up the HD version too, which is smart.

You get a neat recording function In QuickTime, so you can record audio, video or the screen (with or without audio), so you can do those posh-looking demos or tutorials in a flash. These options are conveniently sitting in the File menu, just the sort of place that could be missed, but worth playing around with.

There are plenty more though, like the naming of screenshots are now date formatted rather than "Picture 1", the wireless icon now showing that it is scanning for wireless activity, or letting you know if your battery needs replacing.

Finally, something that will appeal to business is the in-built Microsoft Exchange Server 2007 support. Apple make pains to stress that Snow Leopard is the only OS with this support out-of-the-box and it is potentially a significant point that could really start this review off, rather than languishing at the end.

We saw a set-up demo of this and it is as simple as entering your email address and password, when Mail, iCal and Contacts will sync with Exchange, so long as you are running the right version of Exchange. Very neat, and will no doubt benefit business, if not the majority of private consumers.

Price when reviewed:

Overall Snow Leopard is a worthy update to Leopard, a fine OS in itself. The changes will make a difference to your daily tasks, especially for those who tinker with video, where the QuickTime trim and video view in Finder are very handy.

But from a top-down position you might be tempted to wonder what you have paid for. Sure, there are some real changes here, but couldn't some of them rolled out through regular updates? QuickTime, certainly, would normally be the sort of thing you'd expect to get for free.

One of the big points here is shifting over to 64-bit applications, and Finder in particular. Snow Leopard is a mixture of 32- and 64-bit and we will see the roll-out of future 64-bit application versions in the future, which is when all your favourite third party apps should get significantly better, hopefully.

We'd like to think that Apple was in the position with Leopard to apply an "if it ain't broke, don't fix it" mentality and that's what Snow Leopard feels like. It makes Leopard run like you think it should have always been running. For us, that's enough: we like the changes, but we’ll forgive the cynics who see this as a simple update.

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