A couple of weeks ago, Spotify launched its iPhone app v0.4, and after a couple of teething troubles, during which it was quickly upgraded to v0.4.1, it now looks stable enough to offer a quick review.

First up, for those who are new to Spotify for iPhone, here’s a run-down of what it does – which is basically pretty much everything the desktop client does. You’ve got instant streaming of the full catalogue over Wi-Fi and 3G, the ability to store 3,333 tracks in offline playlists, and fast syncing between mobile and desktop. Essentially, Spotify for mobile puts the entire Spotify catalogue into your pocket, making it instantly available in very high quality. So what does v0.4.1 add?

New features include the much-requested Last.fm scrobbling – a long-standing feature on the desktop client, and a refreshed look. A major addition is iPod integration, which uses tracks already stored in the iPhone’s iPod in Spotify playlists, saving memory and sync time. Also new is the ability to stream at low bandwidth (98kbs) when without a Wi-Fi signal. The new Starred feature allows you to star and save favourite albums and tracks.

The are also other small tweaks, such as the fact that the volume slider has been replaced by the iPhone’s master volume control, a restore feature that means the app restarts where it left off, and the ability to share tracks and open Spotify links direct from the browser and other apps.

Unfortunately, v0.4 was buggy, in some cases causing the app to hang or crash. To Spotify’s credit, they were quick to release v0.4.1, which fixes some of the problems. Some users are apparently still having problems with the iPod integration feature causing crashes. v0.4.1 allows this feature to be turned off until the bug can be properly fixed. I’ve not experienced this bug, but I have found a couple of other annoyances.

A major gripe is that, presumably due to the iPod integration, after updating you lose all of your offline content, and need to sync it all again. Depending on how many offline playlists you have this can take many hours. It was most likely necessary to accommodate the new features, but there should probably have been a warning issued before installation.

Secondly, it is still annoyingly difficult to add albums or tracks into new playlists. (For the record, you need to go to Playlists, click Edit, click ‘+’, create a new playlist, then search for the album or track to add.) It’s much easier to do this on the Symbian Spotify app.

Thirdly, the app seems slightly slower to respond. This could be because it seems to be constantly syncing offline content, but I’ll keep an eye on it and report back.

Another much-requested feature was the ability to listen to Spotify in the background while using other iPhone functions. Unfortunately Apple still don’t allow third party apps to do this, so v0.4.1 doesn’t offer a change. However, the word is that Apple’s forthcoming 4.0 iPhone OS will allow multitasking, and hopefully Spotify will be quick to update the app as a result.

Overall, although slightly flawed, Spotify for iPhone v0.4.1 remains an essential application, effectively rendering the iPod (and iTunes) obsolete. It’s free to download from the App Store, but you’ll need a Spotify Premium account to use it, which costs £9.99 a month.

Mobile network 3 is offering its users free Spotify Premium access for a limited period.

All 3 users can try Spotify Premium for free for a month by texting ‘Spotify’ to 39000 from their 3 phone.

Additionally, those who are new to 3 can get two months free Spotify Premium with the Sony Ericsson Vivaz and X10 handsets, which are available for £35 a month.

If you’re already with 3 you can get a month of Spotify free when you subscribe to Spotify Premium.

3 also offers 24 months’ worth of Spotify Premium bundled with a selection of Nokia, Samsung and HTC handsets.

Get more details at the 3 website.

So you love listening to Spotify on your desktop, and you can put up with the adverts and lower streaming quality, and don’t need the offline mode, so haven’t upgraded to Premium? Fair enough. But by not upgrading to Premium you’re missing out on Spotify’s killer feature – Spotify Mobile. Putting Spotify in your pocket, Spotify Mobile is the essential reason to go Premium. Here are ten reasons why you need Spotify Mobile:

1. It’s free… As long as you have Spotify Premium. Get the app here.
2. It offers access to the entire Spotify catalogue, instantly, via your mobile phone. What’s not to like about that?
3. It’s available on iPhone, Android and Symbian (including Nokia, Sony Ericsson and Samsung) handsets. Get a full list of compatible handsets here.
4. The offline mode allows you to store 3,333 tracks on your mobile and listen to them at any time, even when you have no internet connection. That’s a huge catalogue of downloaded tracks stored on your phone.
5. The Spotify app is simple and easy to use. Features vary slightly by handset, but you can enjoy almost all of the features of the desktop version, including instant playback.
6. Sound quality, at 160kbps Ogg Vorbis (roughly equal to 192kbps mp3 and the same as Spotify Free on desktop), is very good. It’s not as high as the 320kbps Premium users enjoy on desktop, but it compares excellently against mp3s played on mobiles, and for example Spotify Mobile on the iPhone offers a better sound experience than the device’s iPod function.
7. Spotify Mobile streams over wi-fi or 2.5/3G brilliantly. Download of offline content is obviously much faster over wi-fi, but Spotify works great for those relying on 3G too.
8. Syncing between the Spotify desktop client and mobile app is instant, and very impressive. Basically, add or amend a playlist on your desktop, and it will update on your mobile – and vice versa.
9. Cover art – a longstanding annoyance for iTunes and iPod users – is never a problem on Spotify Mobile, with large, high quality cover images attached to every track in the catalogue.
10. The ability to force offline mode means you can listen to your offline content without worrying about data charges, for example when travelling abroad. You can listen to your offline content for 30 days without going back online.

In putting instant access to a huge music catalogue into your pocket, Spotify Mobile is changing the future of music consumption. There are still improvements to be made, for example the Spotify apps do not yet scrobble to Last.fm, but these are minor quibbles considering the benefits the service provides. Overall, if you like music, have a compatible mobile, and live in an area where Spotify is available, Spotify Mobile is completely essential.