I've definitely noticed a definite shift here. I joined back in 09ish, and it was a great forum. Threads were fun, people would quote my posts with informed points, and they would respond to any arguments I made. I had a lot of really fun debates on the escapist.
Now, I almost never get people quoting me with informed opinions. Instead, I see more and more people who have one argument that doesn't make sense and just repost that argument against every logical post I make. Just as infuriating, they often don't even address what I said. More recently, like last few months recently. I've also noticed a lot of threads that were almost definitely started to troll the forums, and perhaps equally bothersome, it works.
Furthermore, you see a lot of people who make legitimate posts get warned or suspended or banned, when immediately adjacent to those posts are posts that bring less to the discussion and are more offensive. And even worse, I see a few specific users repeatedly make posts with no value, or posts that blatantly have no purpose other than to piss off other members of the forum.
All in all, the community hasn't just gone downhill, it has ridden down an avalanche at full speed. I have been seriously considering leaving the escapist for the last few months, but I keep hoping that in just a few months, something will happen that will help bring the escapist back to what it once was. Unfortunately, that seems less and less likely every passing day.