Faith gave me the chance to lay my filthy hands on a Nokia N9 this weekend. Not very long, but at least it gave me some impressions:

First of all the UI as smooth and snappy as in the videos

It looks really great to use! Trying to push it, the only time i saw a hiccup was the first time i got the notifications drawer out. I'm not enough of an iOS user to be able to compare, but my impression was that speed and animations were better than on my Nexus S running Android 2.3.4

Swipe to switch apps rocks

Swipe to switch apps is like the Dude's carpet. It really ties the phone together. It works like this: when you swipe on the screen, it is a normal swipe that for example browses photos in a gallery. When you swipe from the edge of the screen, it switches apps. The difference felt very distinct and far easier to perform than the 4-finger-swipe-to-switch-apps in iPad on iOS 5. 

Browser: 3D CSS Transforms, CSS Animations, Homescreen apps 

So during the few minutes i had i had the chance to run a html5test.com test. I don't remember the exact score, but it was something around 300. Accordning to the site, iOS 5 scores 303, so i guess they're around the same. The features are quite different though. Let's do some comparison:

According to the Nokia engineer i spoke to, the phone supports CSS3 3D transforms and CSS3 transitions and animations. I can't applaud this enough. He also claimed the phone to have good support for the application cache manifest, as well as Local Storage + WebSQL. This means that Nokia goes down the Apple path, and don't support the IndexedDB type of local database used by Google and Mozilla. According to the engineer i spoke to, they also included javascript touch-events and gesture-events, detecting up to 5 fingers on the screen.

One peculiar thing is that you can't actually bookmark a web-page. Only place it as a home-screen app. In the category "no's" we'll also find Websockets and WebGL. I honestly forgot to check whether it supported the DeviceMotion and DeviceOrientation javascript APIs for the accelerometer. So if you get the chance to check that out, please let me know!

On the video side, the browser supports the MPEG4, H.264 and Ogg Theora codecs. That means no WebM.

The browser priorities are right 

Whether this makes the phone and its' browser good or not is too early to say. But as a web developer i say that i have the impression that Nokia got their priorities right. CSS3 transitions and 3D animations might be eye-candy, but it's really important for creating user-friendly, touch-enabled websites that even comes close to the feel of native apps. While i pity the exclusion of websockets, I wouldn't prioritize WebGL for mobile on this point. Don't get me wrong, i think WebGL is one of the most interesting technologies to show up lately, but it still has to prove its' user value beyond cool demos and videos.