Picture the scene. You love the desktop version of Spotify, but you don't have a phone that works with the mobile version. So you go out to buy a smartphone. You've got to pick between an Android handset like the HTC Hero or Galaxy i7500, and the iPhone. Which works better with Spotify?
Running in the background
Many users have found one major problem instantly with the iPhone Spotify app. It can't run in the background, so if you get a text or email, and want to reply, then you have to shut down the music and start it up again.
That's not Spotify's fault - it's a drawback of how Apple has chosen to operate the iPhone. The rationale behind it is that if users have a million apps running in the background then the phone will start to slow down, and the user experience will be inhibited.
The Android operating system doesn't have any such drawbacks, so you can keep listening to music while doing whatever you want with the phone. That's certainly going to be a deal-breaker for some people. Symbian's S60 operating system, which we saw Spotify in action upon on Monday, also allows background running of apps.
Both apps looks fairly different, despite sharing much functionality. The iPhone app has a light background, whereas the Android version takes a darker approach to music streaming. Which you prefer will be down to your personal taste, but neither look out of place.
We've heard a couple of reports that the Android app's interface isn't quite as smooth as the iPhone's - especially on lower-end handsets. It doesn't let you flick between tracks with a finger-swipe, instead demanding a button press. There's also tales of bugs with the T-Mobile G1's keyboard and the application.
Both platforms allow you to cache songs for offline playback, but one interesting fact is that the iPhone only lets you cache when you're on a Wi-Fi signal. The Android version lets you cache on Wi-Fi and on 3G.
That has a couple of results. On the one hand, Android users get to choose how much data they want to use - they have the option as to what they want to do. On the other hand, iPhone owners won't be faced with whopping data bills because they've forgotten to turn off a setting.
Given that phone networks advertise their internet packages as unlimited, despite them being actually rather on the limited side, we wonder if Spotify's app will lead to a flood of traffic on data networks and litigation over what "unlimited" really means once people get hit with overage bills.
3.5mm headphone jack
Lastly, you might scoff at this, but it's important to note that every edition of the iPhone and iPod Touch has a 3.5mm headphone jack for plugging in whatever headphones you like. It's not the same for Android.
Only half of the Android handsets on the market have headphone jacks, so unless you get an HTC Hero or Samsung Galaxy i7500, you'll need to be fiddling around with adaptors to get a pair of decent headphones working on the device.
Sure, there are people who're happy with the headphones they get in the box with their phone, but the majority - especially those who are into music and would be more interested in paying £10 a month for Spotify Premium. Owners of the HTC Magic or T-Mobile G1 will have considerably more hassle to listen to music on their handsets.
Balancing up both sides, it's clear that while Android has a few minor problems with its Spotify application and platform, the fact that it can operate in the background is a very very major plus. For us, that pushes the Android version of the app above the iPhone version.
There's also the fact that Android's bugs are likely to be quashed in future versions of the application, whereas Apple isn't likely to change its policy.
A Symbian S60 Spotify app is confirmed, and there's almost certainly Windows Mobile and BlackBerry apps in the works, so soon there'll be a lot of Spotify options. For now, though, we reckon it's Android's day in the sun.
Update: Thanks to Afront in the comments, a few other differences have emerged. He points out that you can upgrade your storage on Android handsets with microSD cards, whereas you can't on an iPhone or iPod Touch.
He also mentions that the "What's new" tab is present on the Android version, but missing for the iPhone. Though we'd be curious to find out how many people actually use that page when they start up Spotify.
The iPhone version does have a couple of UI niceties that we hadn't detailed - it can open Spotify links from websites, which the Android version can't do yet, and the iPhone version's artist song list is split up sections for singles, albums, EPs, etc, and artwork.
Peter from Sweden adds that Bluetooth headphones are a potential solution to the some-Android-handsets-lacking-3.5mm-jack issue, and that the remote control on his headphones will happily operate Spotify's play/pause/skip controls.