First reaction is very positive - the new wallpaper is great to show the new ability of setting a background for Springboard.
What can i say about yesterday´s presentation? I´m very happy with some changes (multitasking, internal notifications, mail.app improvements, gamecenter - i called this one in my predictions, folders), but i´m VERY angry with Apple for not doing anything regarding what i think is the main problem on iPhone OS - the POOR way that notifications are handled! I mean, we´re in 2010, the competition have shown how to do it in a usefull, non-obtrusive way, and we have to put up with the stupid popups in the middle of the screen...really Apple? Funny thing is that we will have even more types of notifications to deal with, making the problem even bigger. Thank God for jailbreak!