Wizards have a lot going for them, and they do not give up that much compared to earlier eds. A 3e Wizard got no armor, 4 hps, and poor weapons that he'd actually have to fall back on quite a bit early in his career. The 2e & 1e wizards had it even tougher. That early suckage was compensated for by an ever-growing customizeable list of abuseable spells as you leveled up - as long as everything went your way. When things went badly wrong, you could still find yourself reduced to commoner in pointy hat at any time. The Wizard was the most poorly balanced character class in the history of the game, throughout the history of the game.
4e tries to change all that. The 4e wizard has 10+CON hps, and no reason not to take a good CON (STR being emminently dumpable). That's compared to 12 for most other classes. Oooh, you're down /2 hit points/ compared to the Cleric, Rogue, & Warlord. You get 4 hps per level. So you're down 1/level after that. You have good WILL, and your INT - your primary offensive stat, bound to be 16-20 to sart, adds to your REF /and AC/. You can take feats to wear armor. If you're in leather, your AC is probably 16, +1 if you're a staff wizard. The Cleric in Chainmail? Yep, AC 16. At worst, CON is your third priority, so you probably have at least +4 hps, and a 12 FORT. Not great, but probably pretty close to the Rogue. True, your weapons are unimpressive, but, really, who need's 'em. You can cast Magic Missle 14,400 times per day, and it counts as a basic attack.
So, really, honestly, the Wiz had 2hps+1/level to 'make up for' vis-a-vis most other classes. That's less than a single healing surge worth of hps.
You have another at-will attack spell, too, that's better than magic missle, and you have unlimitted use of 4 cantrips, too. On top of that you get your encounter and daily spell (and you get to switch out your daily every day, something no other class gets). The spellbook, alone, probably makes up for the Wizard's slight frailty, but, he also gets his Implement speciality, and undisputed mastery or Ritual magic, prettymuch for 'free.' Rituals are few, now, but can you doubt that there'll be splatbooks full of them coming out?
So, no, the Wizard isn't weak - he no longer experiences the extraordinary swings in power that he used to - but, he has exactly the same number and utility of powers as every other class (as all classes do), perfectly competative class features, /and/ rituals /and/ the unique ability to swap out dailies and utilities every day. All he gives up is a few hps.