Great first try! The main problem for me are the arms / tentacles. They are very undefined and really need some texture and detail. think about when you paint it, it will be hard to make it look convincing with so much smooth texture. I don't know how you sculpted this exactly, but I would recommend sculpting parts like that completely seperately and attaching them to the model when you've achieved the look you want. Keep at it and good luck!
very nice work, good idea and concept. Now, I'm no GS expert myself, but I would suggest adding finer definition to his/her/its legs, and maybe that uppermost arm could use some claws, as it seems kinda formless atm; though maybe that's what you wanted. Anyhow, great work, sorry I can't give more advice. Happy painting :) ~Blll