I like it a lot, but fix the outline of the gray tentacles. Same goes for the crooked shading inside them. But the dark colors of the non-shiny form make it so hard to notice that you can probably get away with it.
Anything else I can think of is that the right gray tentacle is missing its tip, and the glowing part of the left raised tentacle is thicker than the right’s. This second thing is minor though.