First off you aren't really sacrificing actions most of the time. Theres no duration so you are wandering around the dungeon as a centaur or arrow slug or ape man or what ever.

2nd off if you have a modicum of int you can have enough skills trained and have the rest available available at the low low cost of an arm or a leg. Making you the best(or one of the best) skill monkey (you can boost dex to get over the cross class non-bonus)

Also in raw combat potential you outstrip(not quite at first level) every one else in offense and defense WITHOUT MAGIC ITEMS
First level you can use your claws 1d4 and still get DR 5 (average great sword damage is 11 with a 16 str spears are at 8.5 short swords are at 6.5) you still take damage but it's arguably better than armor.
Or you could get natty armor +2 (thats leather armor, not bad) and still use your claws AND get 2 1d6 pincer attacks (claws can go on your feet you know)

Further more, you actually do have a good bit of control, between push/pull, swollow whole, and web

So it's not really that you are better than or equal to casters, it's just that you are still better than every one else.