Multi-tasking is still a bit sub-par as compared to N900's method of multi-tasking. Closer to Palm since it's a card based method that looks like it was spawned from WebOS.

Live tiles still do not seem to be as functional on some apps as they claim to be - 1st party apps inclusive. It's on par with iOS notifications in the sense of how delayed it is.

I can still bog down a 1ghz phone rather simply with just a few (I'd say unoptimized) apps rather quickly. The UI remains swift; however it takes longer for apps to load up data - MSN Onit is a prime example. Takes it forever to load data; whereas Pulse on Android is pretty damn swift and they do the same thing.

The browser is the biggest improvement... it truly moves it closer to my like of Dolphin HD or MicroB. Not perfect, still lacking the Adobe Flash that I like (I'm a Flex dev) but it's a noticeable improvement. It's gone from a 1.0 to a 3.8 on a scale of 5.0.

The e-mail client grabs, but doesn't seem to sync IMAP correctly... still. The speed has improved, it's a lot better than Modest; however I've had better. The threaded look is better than before though. There's a ton of improvement needed here.

Music - I'll admit it. I own a 120gb Zune. Still use it, still love it. So my experience there is great, it's improved on speed and transitions (background) don't seem to slow it down. So the improvements there are fine.

Copy and paste... ok this part pisses me off. I can copy but paste only once. WTF. Sometimes I need to paste multiple times. Not being able to is just plain weird. I can understand copy/paste once on raster images and the like. But links? Or text? I dislike that limitation.

It's still a pain to customize, the tiles are different colors for some apps - my OCD kicks in and I like things to be uniform or at least similar.

There are other things, like the planned addition of forward facing cameras, better memory management and some other features that directly address what I'm looking for in a phone. But after having integrated Google Voice on Android - I use GoVoice on WP7 - and having my updates come in on a timely manner, GoVoice and all of the apps seem to delay on notification. It's bothersome. IMAP e-mail is the exception... but it still feels a tad bit delayed versus Google's GMail level of integration, better than Modest - which seemed to sync just fine, but not all of the time.

There's tons of apps that I consider necessary, but missing - Skype for instance. IM+ Pro is what I use and it just... seems SLOW AS HELL. N900 kills the level of IM integration here. Downright kills everybody to be honest.

So yeah... there's some deficiencies in the apps, features, battery life (better than N900). I love the UI, dislike the delays on loading stuff - just feels more sluggish than a 1ghz processor.

Hope that answers your question.