I'm coming from the Pre after many years with windows mobile phones...
First of all, Android was made for me, that's not necessarily a good or bad thing, but it's a very good thing for me.
There's a reason tablet makers, media device manufacturers and even ebook readers (nook, etc...) use android: it's a fully baked os that can be skinned and embedded however you want.
That said, coming from webos, it's obvious that google hasn't been as concerned with how it gets baked (Sense is integral to the Evo experience). To their credit they're making some solid UI moves with froyo, but a big part of my ui experience on the evo was designed by HTC, who have done a decent job with sense.
I love that I can have whatever granular experience I want, but I'm not everybody. Google needs to keep moving towards making the stock UI good enough to be beautiful and elegant out of the box, and then people like me will add onto, rather than replace the default UI.
What I like:
Flexibility: Because it's a fully baked linux build, you can make this phone do whatever you want. It comes closer to being a fully functional computer in your pocket than any other phone I've used.
Apps: It's not the runaway train that is the apple appstore, but it's exactly the sweet middle between the iphone and the pre. There are a lot of apps, but more importantly, there are a lot of apps that do some pretty incredible things. Because it's an open platform, there are apps that really extend the functionality of the device, rather than just adding chrome to the fender.
speech to text: It's a button on the keyboard, and it works pretty well. You can speak your searches, emails, texts, whatever, and it'll do a manageable job. (i.e. it might use the number 4 when you meant "for," but it won't trash your sentence). Really definitely a nice feature, and it works well enough that I would actually use it more than I ever did on windows mobile (and webos, sadly has no voice control).
screen: I'm much more likely to make this my go to device for light browsing on the couch, etc... at this screen size. The browser is solid (plus there are alternatives available), and it's zoom reformats at exactly the right point, giving you the flexibility to devour web content in a 'slightly' more intuitive way than the pre browser. Plus, if you don't love that - well, I've got firefox, dolphin HD, or whatever else you might like to try. (and yes, I did set up weave on fennec almost immediately... the browser isn't ready for primetime yet, but it's good enough that it took me a moment of weighing the benefits of universal sync vs. a fully baked browser). For now, Dolphin HD plus google bookmarks, gets me 90% of the way there.
screen: no seriously, children will sing songs of this screen.
google integration: webos was awesome at this, but it's kind of not a fair fight, and I can't hold that against palm. It's not fair to ask another company to integrate with google better than google.
what don't I like:
Lake of continuity of interface: okay, so that's a mouthful, but basically, while there are dedicated menu buttons, which generally I like, I'd like it a lot more if settings and functions were in the same place throughout apps.
The app store: how about some sort options. I mean, isn't Google kind of into search? Can I organize by rating, release date, body weight? something? No? just relevance (I guess?) cool. At least I have appbrain to keep me from grumbling too much.
The camera: meh - it's a lot better than the Pre's (which was fixed focus and took super grainy pics in low light), but it's not the Point and shoot replacement I was hoping for. It devours barcodes though.
---
The battery: I'm getting 10-11 hours of fairly abusive usage. 2 things I've noticed: 1) GPS will eat your battery for lunch. 30 minutes of google maps nav and I lost 30% of my battery, the remaining 60% took me another 9 hours to go through. 2) 4G does put the burn on. I've been toggling it based on when I need it (i.e. streaming audio on the commute), and turning it off if I'm just browsing lightly. Ultimately though, the reviews which have trashed the battery (mobilecrunch, techcrunch) must have had bum units if they're only getting 4 hours of "moderate" usage out of it.
Ultimately, Android is a great fit for me. A better fit than webos, and I'll be more productive and happy with this phone, which considering how happy I was with webos, says a lot. That said, I'm still going to recommend webos to some people for it's accessibility and elegance, but this won't leave my hands anytime soon.
As a side note, a member of my staff came into my office today, not very tech saavy and all, and she looked at my phone, and immediately lit up, knew all about it, and how her cousin gave her whole family a demo of it over the weekend. The hype is here for this phone in a way it just wasn't for the Pre.