One thing to remember is that werewolf attacks are based on your 1-Handed weapon skill. And you can't level up skills including combat ones. The biggest issue to me is you can't pick up anything, either.
This isn't true...
Unless an update has changed it, the game guide has the following chart..
base: 20
lvl 11-15: +5
lvl 16-20: +15
lvl 21-25: +25
lvl 26-30: +30
lvl 31-35: +35
lvl 36-40: +40
lvl 41-45: +50
lvl 46+: +60
So you cap out at doing base 80 damage. I believe this is because your are using your claws, it is unarmed damage you are doing. I don't think that this stacks with the Kajiit's bonus
You gain 100 pts of health but lose the passive regenerative ability.
Feeding provides a 30 sec (real time) addition to your time as a werewolf (you start with 2 min and 30 sec) and you heal 50hp.
Your initial howl can be swapped out for one of the two others if you wish.
The ring only allows you to turn 1 addition time per in game day.
You get a 100 point increase to your stamina.
While in form, wolves will treat you as an ally.
You can get away with murder but if you are caught changing by npc's (other than bandits and the like) then it is considered a major crime.
All your gear is unequipped and unfortunately there is no unarmored skill (though skill progression ceases anyway).
Can't cast spells, can't loot corpses, can't access your inventory or list of spell/shouts/powers (but can use the shortcut keys for map and journal).
Can't pick locks and maybe can't use keys (though if you need to loot a corpse, chest or pick it up off a desk then you're SOL anyway)
Can't pass through some smaller openings due to your large size.
Other werewolves will still attack you if you are in human form. I can't confirm if they do or not when in werewolf form.
Immune to diseases
Can't get resting bonuses
Last two are separate because they effect you in human form too. In all honesty, I find that most of the time, my human form is more powerful.
There is just one mod that I want and that is to make changes to this form..
1. Rather than an increase to the hp pool and no regeneration, I would like a 50 point increase to health (this is something your character gets upon becoming a werewolf and is not form specific) and have a regeneration equal to that of trolls while in form.
2. Wolves and werewolves treat you as an ally in human form too.
3. The ability to change becomes available between 9pm and 6am only (or whatever the time gap is for night, excluding the twilight hours). Time is doubled so you start with 5 min and each corpse you feed on adds 1min. (Ring works per normal) Edit: If you used the raw power (not the ring) and accumulate enough time to make it past 6am, you will change back anyway.
4. 20% weakness to silver weapons, 10% weakness to daedric and enchanted weapons. 10% resistance to normal weapons. while in werewolf form.
5. Weakness and resistance cut in half but still there while in human form.
6. 25% of your base damage in werewolf form (see chart above) is added to your unarmed damage while in human form.
Edit2: Also, from what I can tell, you can't jump any higher and it's your sprint that allows you to "run faster than a horse" although you do run faster than normal.