The only way to become a werewolf seems to be to join and advance within a certain guild. This is an unwanted limitation on what type of character can become a werewolf without forgoing a sense of roleplaying: Anyone not playing a certain type of character must join an ill-suited faction to gain the power (and further, from a roleplaying perspective, the character has no knowledge that the faction is the keeper of that power, eliminating the possibility of playing at manipulating the faction to gain what the character wants).
Werewolves cannot sneak while in beast form (contrast this to werewolves having a set 95 Sneak skill in Morrowind). These werewolves aren't hunters but instead DPS warriors with some crowd control (fear-inducing howl & possiblity of knockdown w/power attacks).
Werewolves cannot perform the superhuman leaps of which they were capable in Morrowind.
The mechanic of feeding to maintain beast form is not implemented well. Only humanoid creatures of playable races can be fed upon, significantly reducing the usefulness of the power in dungeons and areas not dense with such enemies. Given that limitation, the default duration of the power (180 seconds) and the extension from feeding (30 seconds) are far too short. As a further limitation, the power can only be used once per day.
Wolves aren't hostile when in beast form but fail to recognize the character when in human form. This is just f***ing assine considering guards comment "You smell of wet dog!" Guess those guards have a keener sense of smell than wolves? WTF.
Tbh, I use my werewolf power primarily for transportation in wilderness areas or on lonely roads: Werewolves can sprint as fast a horse, which makes for a nice substitute given how stupid horses sometimes behave in this game. Sometimes I use it to kill groups of bandits I stumble upon. That's about it. :-|
Would it have been so difficult to take basic mechanics of Morrowind werewolves, patch up its flaws, level the power to increase with character level to avoid an overpowered mechanic, and add some nifty extras? Modders have done it for Morrowind and Oblivion, but Bethesda can't do it? Obviously they could have done so but preferred to shoehorn werewolves into their crap concept of "warrior, mage, OR thief".
Eh, that's enough ranting from me for now.
To end with something positive, I'm enjoying the game more now that I'm frequently using a bow. The ability to "de-nock" or "un-nock" (or whatever) an arrow is a great mod-inspired change from previous TES games.