At first glance it seems pretty lackluster, most MMO's release with twice that many classes, if not three or four times as many - but I also get that in TESO we'll basically be able to create our own class once we get into the game, and that these are really just starting points to give us an initial way to tackle the world.
One thing I'm wondering is how, exactly, they've split up all of those abilities. We know the dragonknight has abilities like his chain-spear to pull enemies towards him, and we've also heard that the Sorceror's class skill trees are Stormcalling, Daedric Summoning, and Dark Magic. Given those tidbits of information - do you think that a Dragonknight could, through advancing magic skills, learn how to summon daedra? Or that a Sorceror, if he advanced his skills and character correctly, could learn to use the chain-spear? This is my main point of confusion in TESO's class system: we're told we can pretty much do anything with our characters, but then we're given these class-specific skill trees that seem to limit us in our basic abilities.
At the moment, I'm thinking that it doesnt work that way - Sure a sorceror could use heavy armor and a greatsword, but I'm not sure he'll ever gain access to the chain-spear ability, nor do I think a dragonknight or templar could summon daedra. It seems to me that each class has skill trees that are -only- available to that specific class, and that's what really seperates all of the classes from one another even through level 50. If you want to be a warrior-like character that summons daedra, you'll have to roll a sorceror and then focus on your armor and melee skills - if you want to heal, you'll have to roll a templar and focus on healing skills.
I'm also guessing that outside of class abilities, magic use will probably be limited to magic-based weapons (staves and runes). A templar may not get any destruction-type spells, and wont be able to actually advance in destruction magic like a sorceror could through the stormcaller tree, but he could use a destruction staff or destruction rune and advance that weapon type to give himself similar abilities to the destruction spells a sorceror might wield.
This is all still speculation of course, but I'm curious to hear what other people think of the subject.