I avoid Early Access stereotyping. Some games in early access clearly are crude alphas with some promise of enhancements/improvements over time. Some are pretty polished games where you only get to play a small-medium chunk of the game. Some are kickstarter projects that have been around quite a while and moved into Steam Early Access to get feedback from a wider player base.
I always see Steam forum posts bellyaching about not wanting to be "unpaid beta testers," but the reality is a lot of the early access projects are by smaller teams and dev houses that can't afford a large, professional testing team. And God knows we've all played lots of half baked $59.99 msrp release games that play as if nobody tested them at all. Nobody's forced to play early access, so I'd steer clear if the whole "playing something that's not done yet" angle ticks one off.
Have been extremely pleased with playing these games during Early Access:
-Assault Android Cactus
All three titles are updated regularly, if not crazy-often regularly. You can see the devs are invested in them, and at least to some extent pay attention to player feedback. I'd be leery of early access titles that haven't been updated in ages, or where devs seem to be consistently ignoring player feedback.
To me, the Divinity game that's currently in early access is an unoptimized, prematurely released mess, and the latest update has caused it to lockup repeatedly. I gifted it to a Steam bud who likes co-op stuff, but we both agreed it's a mess, and I shouldn't have bought or gifted it.
Not to mention the gameplay has very little to do with any of the previous Divinity titles (whether the 3rd person game before this, or the older isometric Diablo-style titles, and while it's technically turn-based combat (which I love), I would steer people over to Blackguards or The Banner Saga first..
I guess the lesson is "buyer beware" and sift through player feedback carefully before you sign onto one of these things.