When I first got the books I was shocked at what looked to me like the nerfing of wizards. I knew vancian spells were out but it worried me to see that mages only got something like a choice of 4 spells per encounter, not counting the 2 or 3 at will spells you have, and always the same 3 at will spells, but as I studied the new encounter system it occurred to me it's ok. Sure you have less spells at first glance, but you can reuse them every encounter. Just pray the DM isn't the sort to throw in new enemies every round, that way the "encounter" never ends. You need to have a break, even if only for a few minutes so you can reset when it starts again. The really powerful spell stuff, the stuff which I think seperates the wizards form other classes with just as many powers, are rituals. Sure a fighter might be as powerful in a fight, but he can't spend an hour summoning something big. I thought from a story viewpoint the fact that failing stuff like wilderness travel rolls takes away healing surges, so if you mess up and spend all day walking around the middle of nowhere you'll tire yourself out, is a good touch.
If you haven't already I suggest listening to the Penny arcade session. It does give a good idea of how it works, just be careful if you don't like harsh language.
http://www.wizards.com/default.asp?x=dnd/drfe/20080530
http://www.wizards.com/default.asp?x=dnd/drfe/20080606
http://www.wizards.com/default.asp?x=dnd/drfe/20080613
which reminds me, I've only gotten a third of the way through part 3