3d6 said:
The wizard should deal more damage for those two rounds he's casting spells. That's pretty much the only way he meaningfully contributes. As it stands now, over 4 rounds, the archer probably has dealt more damage. Over 8 rounds I guarantee it.
As stated above, the "issue" (if it can be called that) isn't the amount of damage. 1d4+1 isn't anything special, even at 1st level. 5d4 + 5 isn't that great at later levels. What MM has that other spells don't is longetivity.
The ability to have a guarenteed hit at 1st level is great, although sleep or mage armor may actually be a better bet at that level.
At 5th or 10th level the first level spell is still useful. High touch AC? Magic Missile. Evasion? Magic Missile. Incorporial? Lots and lots of Magic Missile.
At 20th level, a first level spell still gives a guarenteed hit*. That is something a 20th level fighter can't boast on a kobald (he might roll a 1 - even on a the rerolls - well, except for Weapon Supremecy from PHB2 - I guess he can boast it: after 18 levels - my point still stands). Magic Missile still has certain uses at high levels. A first level spell.
Magic Missile: when you absolutely, posatively have to kill that wraith in the room; accept no substitute.
Note that I don't think it's overpowered. The damage isn't that great. People who do think it's over powered (I'm not one of them) raise the issues described above.
*There is Shield, SR, Wall of Force, Brooch of Shielding, etc. But you know what I mean.