I was just in 20A. It's very private. That could be good or bad, YMMV. Arguably claustrophobic, although there's a smidge more elbow room than on, say, a 777. You can't really see anything that's going on in the cabin, as you're staring at a bulkhead wall and can only barely peek over the seat divider.
You'd have to rely on the FAs checking in on you for any service (fortunately I had a good FA).