I'm unimpressed by their WinMo offerings, but the Android ones... Much better!
The Hero seems like a huge improvement on the G1, and G2/Magic with the new interface. The latest ROM (will come officially soon) improves it alot, takes away almost all lag!
Battery life IIRC is about 1.5 days of heavy use... Not sure. I found the build quality to be very good personally. TONS of free apps in the market place. Very good keyboard for an on screen one. Web browser is very good. The screens thing is great I think, love the little toggle switches you can add for wi-fi, bluetooth, airplane mode etc. - camera isn't so great though, compared to the N97, by all accounts, but I think everything else blows the N97 out of the water.
I used to like Symbian, preferred it over Android on the G1, and WinMo skins HTC did, that just over complicated things, like flicking pictures up and down! Now you just swipe side to side with the Hero when viewing pictures...anyway, the new UI for Android rocks IMO, looks sleeker than Symbian, seems far more reliable, and is so much faster! I was going to go for an N97, and use it for music too, but I have too much, and I like to carry it all, so even an iPhone wouldn't be perfect, especially no expandability, and now i've decided on the Hero, only thing holding me back was the lack of storage, but with an 8gb MicroSD, i'm sure i'll be fine, and i'll just carry my iPod too.
I'll be getting one soon

For now, head to Youtube, search for HTC Hero Review, and sort the videos by their rating to get the ones with the most stars at the top. Some of the 3/4 part reviews are a good 25mins long in total, but worth it to see it all in action, and get a good gist of the phone. Seriously helpful, and gives you the details you asked for in your above post.
Matt