The tablet S overall got pretty good reviews. But it hasn't been a terribly popular tablet, which is probably why it doesn't have its own forum here.
But why hasn't it been popular? Well, my guess is that it was priced too high (just as much as an iPad) and people weren't convinced that the extra money would be worth it. Why spend $500 for an Android tablet when you could get what seemed like an equivalent Android tablet for $400, or even less? Another possible reason is that it took forever and a half to get the thing rooted, which kind of put a chill on that whole area of discussion, which is a pretty big one when it comes to Android.
Personally, I own a Sony Tablet S, and really like the form factor, the screen, and the customization to the Honeycomb UI made by Sony. What I don't like about it is its uncertain future -- it seems Sony is not really sure what they want to do in the future with their tablet line. I mean, for example, regarding deploying Ice Cream Sandwich, Sony just said "sometime in the spring of 2012", which isn't really making me feel too great, both because of how late that is, and also by how vague it is.
But, bottom line, it's a wonderful tablet, and at the prices you see these days, quite worth it. If you do decide to get one, I highly recommend getting the stand / dock. It's great for watching movies, or even just using the thing as an alarm clock.
Oh, and one more thing, which might sway your decision to get one. There are really not that many cases that fit the Sony tablet well. I personally couldn't find a single one that I actually liked -- they were all so butt-ugly compared to the tablet itself, plus bulky, and on top of that, didn't have cut outs for the infrared. So I opted to go for a skin and a slip cover.