Magic-User
There are so many good names for magicians -- Wizard, Mage, The Amazing Zappo -- that it's a pity that the designers of D&D didn't come up with something less stilted. "Magic-User" has so little flair that they may as well have called them "Paranormal Effects Administrators." The other problems with Magic-Users are that at the start they can easily be laid out by even the most lame of subterranean denizens and they have a grand total of one spell per day to use. You cast "magic missile" once and you're dead weight for the rest of the day. Sure, eventually you can cast lots of room clearing fireball spells and the like, but by then everyone's carrying Swords of Casual Dismemberment and Amulets of Pretty Much Instant Death anyway. C-

Thief
You'd think people would catch on that maybe searching out and recruiting people who readily admit to amoral lawbreaking isn't a Nobel prizewinning idea. In the groups I played in Junior High, there was always the thief who loved to practice his pickpocket skills on other members of the group. In retrospect it doesn't make a lot of sense to filch a couple medieval quid from a heavily armed swordsman who's spending his time and energy killing ugly beasts so that you can share in the loot, but Junior High School D&D players have never been known for their social insights. C-

Fighter
Slightly better than "Magic-User" as a name. At least fighter is more specific. You fight. End of story. Fighters make a lot of sense as a character class: you get to wade into battle, the princess always makes a pass at you, and you've got clerics to serve as walking first aid kits and halflings to serve as shields. Names are easy to come up with: just combine a manly-sounding name with a dangerous-sounding title, and whoom! You're Zagor the Bloodletter. Or Palthon the Intimidating. Or whatever. Sure, you don't get lots of little tricks and magic spells and such, but once you find the aforementioned ridiculously powerful magic items you won't much care. B-

Cleric
When I did a Rating of Chess Pieces, I scoffed at the idea of bishops in battle and was served my comeuppance from several astute readers who have a keener grasp of the history of warfare than I. Apparently kicking holy ass is not all that historically inaccurate after all. Thus Clerics, who aren't allowed to use swords because they can't spill blood, as if you can pound a bugbear to a pulp with a mace and still not muss the polish on your riding boots. Clerics also have the power to heal, which has established itself as an important skill in the gore-laced world of roleplaying games. Supposedly this power is bestowed by the gods, but in all the games I've played, healing is treated with all the awe-struck reverence given to ordering an Extra Value Meal. B

Paladin
The Paladin is a holy warrior, basically a cross between a fighter and a Mormon missionary. Paladins are typically played in one of two styles: the "completely overblown" style, in which the character is always going on about God and/or the gods, praying at the drop of a helm, and giving assassins the benefit of the doubt, or the "completely indifferent" style, in which the character pretty much does whatever he wants, only his sword glows. D+