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The are also other small tweaks, such as the fact that the volume slider has been replaced by the iPhone’s master volume control, a restore feature that means the app restarts where it left off, and the ability to share tracks and open Spotify links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

I spoke to Dave Swartz at MEDL Mobile about his company’s App Incubator scheme, and Rob Shoesmith, one of the first applicants to have his idea developed. Rob is recording his progress on Twitter. I also interviewed Ethan Nicholas, developer of the hugely successful iPhone game iShoot, and William Kehl, creator of the website iphonefreelancer.net.

Elsewhere in today’s Guardian, Bobbie Johnson points out that only the developers of top-selling apps are likely to strike it rich. And with over 40,000 apps already competing in the App Store, and 2,700 new ones being added every month, making money from apps is no easy feat.

For those tempted to try app development, Ethan Nicholas offered some advice that didn’t make the finished article: ‘iShoot looked like a relative failure at first, not even breaking into the Top 100 and selling poorly. It took what essentially amounted to an advertising campaign, in the form of iShoot Lite, to spur sales to this level. The best advice I can offer is “don’t give up”.’

[Today's Technology Guardian also flags up this blog's response to an article from last week on digital music. The full blog post is here.]

However, there is a way of listening to your favourite Spotify tracks on your iPhone or s60 smartphone (most Nokias, lots of Samsungs, and a few LGs) without downloading. It involves ‘scrobbling’ your Spotify tracks to Last.fm, which is pretty simple if you’re already a Last.fm user, but if you have no idea what scrobbling means then read on…

The first thing you need to do, if you haven’t done so already, is to sign up to Last.fm. With all the recent hype surrounding Spotify, it’s easy to forget just how good Last.fm is. It’s essentially a personal radio station that builds playlists based on your listening habits. It does this by ‘scrobbling’, or identifying and tracking, each piece of music you listen to. Signing up is easy – just enter a user name, email address and password, and you’re away. And, of course, it’s free.

If you’d like Last.fm to scrobble the music you listen to on your computer or iPod you can download the Last.fm Scrobbler. The more tracks you scrobble, the better recommendations you’re going to get. (I’m currently at 20,284…)

To scrobble your Spotify listening habits, open Spotify, go to Edit and Preferences, tick ‘Enable scrobbling to Last.fm’ and enter your Last.fm username and password.

Next, you need to install Last.fm to your phone. If you have an iPhone or iPod Touch you can download the official app, for free, from the App Store. Nokia and other s60 users need to download the MobblerLast.fm radio player. You can also get Last.fm apps for Google Android phones and the 3 INQ1.

The apps differ slightly by phone, but essentially you’ll now have a choice of personalised playlists, including a personal library made up of your scrobbled tracks, and a recommended playlist based on your scrobbled tracks. You can skip, ban, and ‘love’ tracks, and the app will continue to scrobble as you do so. If you’re new to Last.fm it’s going to take a few weeks to build up enough scrobbles to take full advantage of the service. So fire up Spotify and get listening…

(Bear in mind that streaming music obviously uses a lot of data, so it’s recommended you only use these apps on an unlimited data contract or your Wi-Fi connection.)

[UPDATE: The Spotify iPhone app is go!]