We've had big oozes, small oozes, oozes that drain your blood, oozes that spit fire, oozes that are invisible... ghost oozes were just a matter of time.
These amusing cubic blobs are unfortunately crippled by 12 ooze RHD. They're largely unsurprising: high strength, high constitution, terrible (or nonexistent) stats everywhere else, a single melee slam that deals acid damage, and improved grab/constrict are hardly noteworthy traits.
The most interesting part about the ethereal ooze is how they, like ghosts, exist only physically on the ethereal plane. They can manifest onto the material, but are still incorporeal when they do so. The ooze's signature attack allows it to drag material creatures onto the ethereal plane and immediately start digesting them, which is thematically fun but more than a little impractical.
The need to move into position (with 15 ft. base speed no less) and spend a standard action activating the ability notwithstanding, isolating one foe from the battle so you can 1v1 it is typically a bad idea, especially if you're a near-useless ooze. In battles with large hordes, you're unlikely to put much of a dent in their numbers, while in battles with individual strong foes you will be biting off more than you can chew (which, given the lack of teeth, is very little at all).
Are ethereal oozes fun monsters? I guess: an encounter with one would certainly be unusual, assuming the party has a way to reunite across planes. Are they playable PCs? No. -0 LA.
Next up are the monsters you've all been waiting for: ethergaunts.