The new two finger default page gesture is proving rather problematic for the web-app I'm currently working on (which has a workspace larger than the screen which you can scroll around). If you scroll to the left you can accidentally do a page-back and leave the app. Setting a beforeunload handler actually makes the problem worse because the confirmation dialog doesn't appear until the page has completely disappeared, and if you choose to stay on the page, Safari just shows a blank page instead of redisplaying the app.
I don't quite understand the by-default conflation of two actions (scrolling and paging) using two fingers. It's all very well that I can myself change to three finger swipes for paging, but I can hardly instruct all Lion/Safari users to change their system settings. (I understand that a workspace web-app is rather the edge case).
Lion full screen is by far the most maddenlingly frustrating and disappointing Lion feature for those of us with multiple monitors.
In MacTerm I didn't bother with an option, I just keep my original behavior. I see no reason to change it; my Full Screen is instantaneous and works with 2 displays.
The maddening thing about Apple's new APIs is that the only way to get an official Full Screen icon on a window frame is if you use their Full Screen command. There appears to be no way to let users trigger older mechanisms with the new icon.
It effectively renders my second monitor completely useless.
If you want Lion's "full-screen" mode in Chrome (and other apps, TextMate, Firefox, etc), I made an extension that adds it in: http://chpwn.com/apps/maximizer.html