[Vibrant General] N8ter:
The Windows Search button is context sensitive.

Maybe you're having trouble finding it on the HD2 (keymappings different, etc. /shrugs/ ), but you bring up marketplace search (or search in any app) by simply hitting the search key.

Flash was a huge deal to me, until I see how badly it nerfed the Vibrant's browser performance. Any setting other than off makes the browser perform terribly. The WP7 IE browser runs laps around it. Cutting it off boosts it a bit, but that's terrible since it has Flash Lite before and we didn't have to deal with such terrible performance... I don't hear any of my iPhone-using friends complaining about the lack of Flash.

App are meh. The only thing that matters are complex apps and games. Most mobile apps (non-game) tend to be encapsulations of mobile websites. An Engadget app doesn't make any sense to install, IMO, since I can just go to Engadget.com and the site is optimized for mobile browsers... Same with CNET, etc.

Some apps just aren't worth bringing to WP7. Office apps aren't worth bringing over. NoteTaking apps aren't worth bringing over. SMS Replacement Apps aren't worth bringing over. Exchange Clients. WP7 has Find My Phone/Lock/Wipe functionality built into it, so stuff like LookOut isn't much use (don't care about the sirens, a phone thief/finder will almost always shut the phone off immediately).

I'd say no browser except maybe Skyfire is worth bringing over at this point, because the chances of them outperforming IE on WP7 is slim to none. As far as apps are concerned, WP7 is probably the most consistent (in Look and Feel) and complete OS released to date when it comes to having all this stuff integrated and from a single vendor. Andorid manufacturers usually license different components from dispirate software vendors to "complete" the experience.

Cameras are comparable. Vibrant takes better pictures during the day. HD7 better at night due to the dual flash. The Vibrant tends to get a better framerate on video, but when blown up on a larger screen it looks a bit grainy and washed out (sort of like a painting). The HD7 doesn't suffer that issue, but the framerates are a big lower. I'd say it's a bit of a wash, with a slight edge to the HD7 because the Vibrant simply cannot compete at all in terms of night time picture shooting... It just can't, even with night mode, etc.

As far as the Navigation and smoothness of the system... The animations have nothing to do with it. It's basically iOS performance with extra eye candy to look better. The only thing that lags a bit is scrolling through lists (Android does this as well, but I think the fact that lots of applications load internet data on the fly has something to do with it in some instances) and resuming from apps (which will see significant performance boosts in the March update, among other things).

The animations aren't hiding any lag. We're seriously comparing a phone that lags switching home screens to a phone that can animate pretty much every transition without as much of a hickup. Let's not go there...

The Music Player is not the same functionality wise. WP7 uses Zune. The Vibrant uses the TouchWiz Music/Video player. Zune has FM Radio, can Stream Music if you have Zune Pass, and interfaces with the Zune software on the computer.

Galaxy S has nothing like XBox Live, which is useful even if you don't have any XBL games on your phone because you can send and recieve messages, etc. There are some good games on XBL/Marketplace, though.