I was a playtester but I stopped
The DM who ran D&DN for our group for a short while feels the same way. He just wants the books to come out, and will analyze them at that point. (Our general opinion, and his, is negative.)
Playtests are disruptive if you already have a campaign going, and the results are almost meaningless without metrics, which WotC
is not providing. Playtests for balancing purposes need to be repetitive and frankly boring; in addition to playing games, playtesters should be creating scenarios where PCs of different classes are taking on a group of monsters, running the
exact same scenarios repeatedly, even if it's a one-person game.
The ghoul versus party situation was a shocker to me, not because I'm surprised at poorly-designed rules, but because those should have been fixed one playtest after the ghoul was introduced. WotC acted as if it was completely surprised that the rules were bad.
I also get the impression that WotC isn't listening to me, either because they're settling on certain things or because my opinion is drowned out by a larger number of happy fans (the ones who don't like the way the game is going have probably stopped responding to surveys), but either way this doesn't make me enthusiastic about playtesting.