I downloaded the beta yesterday and promptly spent 4 hours playing it.
I had such low expectations for the game that I found it enjoyable. I did about 4 missions by myself before me and a friend of mine teamed up and did four more.
There's still a couple of bugs (some of my mons would stop rendering inside the ship, friend had to buy ship upgrades twice before they took effect) but all in all it's a fairly well done Diablo clone.
Spore's "skin painter" has gotten more powerful, it looks like (one of the creatures is a rock elemental with glowing lines of cracks showing his liquid magma interior (which glows and animates), and one of his hands is ON FIRE). They've also added robot creatures, I've only played with one that looks like an AT-AT, but there's another my friend was looking at that has two "defense item" slots because it doesn't have arms (it's a tank).
There's limited customization; I'd equate it to being tribe or civ level of Spore where the creature is "done" but you can put stuff on it, although you can tweak some of the body decorations (spines, tentacly things, etc) that aren't the creature's arms or legs. Later on you can strip the stats off items and make them pure decoration, which is cool (friend and I didn't get there last night).
But the game play is more the level of the creature phase, only bigger, better, and with more purpose. There's a plot, so its more of "an adventure" than "survival" but the feel of the gameplay is similar: you control one creature (at a time, up to 3 are in the squad that you can swap between) and beat stuff up. Every creature has its own collection of interesting powers ranging from an artillery strike (hero-mon remains stationary and bombards a target area) to a bramble patch (that slows and DOTs enemies) to teleporation to causing Fear.
A mission encompasses anywhere from 2 to 6 individual maps which range from a large area (for boss fights) to long winding levels across asteroid collections or through forests or caves. Enemies can appear (such as by digging up out of the ground) or visible before you walk up, there are also "oil barrel" items that when damage explode dealing damage to enemies, to "trap" objects that damage your mon until you kill it.
All in all, its not bad. It is, however, not what people expected out of Spore: huge procedural locations, random monsters, true massive-multiplayer, creature creation, etc. etc.
But it is fun.