So far as I can tell (since I haven't yet played with it, but it appears to be moving forward as a new edition)
1) It makes Facebook look like MySpace. Which is not an improvement. MySpace was hideous and lacked any utilitarian aesthetics. Which I enjoy. This makes me wish Google+ was more popular. (And reminds me of the line of "Windows 7 is much more user-friendly than Windows Vista. I don't like that."). I'll assume they will eventually screw with the wall too, but I plan on mostly continuing to use the wall and ignoring the arduous task of perusing personal profiles.
2) It apparently requires several hours of self-censorship and regression through however many years one used it in order to make a profile as presentable as the present version. Which sounds like giving everyone a "job" rather than a sensible way to update the network. I'm not sure, in my opinion, that my most important posts were the ones that everyone commented on or liked. For example. In my case, since a lot of information is concealed or simply not provided at all, I will have somewhat less work than others. The most pertinent information I've made available are quotations or my preferences of culture. Religious or political views are made obvious from what I post. Any actual personal information is pretty limited in who can see it and who will be able to still see it even after this shift goes mandatory. So at best I'll be filtering photos or posts by other people about me, or something.
3) On my screen, the upper bar doesn't fully display. I'll be generous and assume that this is a glitch that would be fixed or a setting I could adjust. This could be related to the image sizing elements of FB more broadly being whacked by timeline however.
4) It appears to be popular enough that most people will just go along with it and/or like it. So either deal with it or move on.
5) Apparently if you want to keep the old school version, use IE7. Except that I haven't used MSIE in over a decade, I don't see a problem with that scenario...