Spotify just announced a free mobile radio app for iOS devices, which has some tech watchers suggesting might mean trouble for rival music streamer Pandora, yet we can still think of one big reason to keep that Pandora in our rotation: Its algorithm. Within the next few days, iPhone and iPad owners will be able to pay zero dollars to stream Spotify, making it a lot like a version of Pandora, which should have the app-based personalized radio service scared, say the techies. But, as a user of both Pandora for the iPhone and Spotify's desktop radio version, we can say that Spotify's song-selection technology just doesn't do it for us. Pandora just picks better tunes. And we know we're not alone in thinking that.

For those who love Spotify's radio and have no interest in Pandora anything, new new app is for you, for the following reasons:

• Radio apps are a nice, casual way to listen to music and now Spotify has one, too. Like Pandora, Spotify lets users pick artists, songs or albums around which to create personalized stations. With that and a fancy phone, users can listen to hours of free streaming music.
• It's a free mobile option that didn't exist before. Until now, Spotify only offered a free desktop version, its mobile apps come with the subscription service. This new offering doesn't provide the full, choose whatever song you like experience, only offering its radio option. But for the cheapos who find that sufficient for on-the-go music listening, this will work.
• It has all that social stuff, if you're into sharing jams with friends on the internet. Songs and radio stations will show up on Facebook. Users can also make stations based on friends' playlists.
• It has inter-device functionality. For those with many a mobile device, it will pick up where it left off. (Pandora does this, too.)

However, the Spotify radio app still uses the same music selection process as the desktop version, which doesn't suit our tastes. When choosing which songs to play, Spotify relies on user data, rather than an algorithm. In theory, that's supposed to help us discover songs based on what our friends like. It's the social Internet at work. But, using the radio app, we don't like what our friends pick compard to what Pandora's Music Genome Project suggests for us. It might just be a preference thing, but The Verge's Ellis Hamburger calls Pandora a "unique algorithmic recommendations engine nobody seems able to match," compared to Spotify's Open Graph-based system. This head to head test conducted by Digital Trends' Andrew Couts says the same thing. "From what we found, the songs chosen by Pandora were, in fact, much more what we wanted to listen to than what Spotify chose," wrote Couts.

Other than that, though, the two apps are pretty similar, even having the following similar downsides.

• Limited skips. Both Spotify and Pandora in compliance with DMCA regulations can't allow users to skip every song they hate. These same regulations also mean users can't choose songs, but only genres of songs.
• Ads. Just like old-school radio, these streaming apps sprinkle adds between listening. It's annoying. It's also what you get for not subscribing.

For those who already enjoy Spotify streaming radio and don't want to pay for the full app, the new version is a cheapskate-friendly option. However, if you're like us, you already enjoy the free Pandora radio app, so why switch? Even if you like the freedom of the desktop app, which lets users choose whatever songs they like, that still costs money on the phone. No need for brand loyalty here.

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