I got myself into the PTR on the first day, somehow. Its quite fun testing out the new stuff AKA me destroying people in duels as a ret pally. That's the current amount of my testing so far. I've been trying to get into Strat to see if I can actually solo it now, although there's been a few screw ups along the way (mainly the test program failing as I sat waiting for a loading screen to finish to get into Strat, and then when I logged back in, it told me that "There is already a character with this name" logged in, so I couldn't log in, despite that being my character with that name).
I was just about to try to get on again, but the American PVE test server had a 645 person queue just a minute ago.
The Patch itself comes with the new Wrath Log-in and loading screens, all of the new 51 point talent trees, a few graphical enhancements (the new shadows, mainly), the new spellpower stat (which replaces the old spell damage and bonus healing stats), the altered stats on quite a few pieces of armor and items, the Barbers in most of the major cities, the achievement system, Stormwind Harbor, and a few other things that aren't coming to me off the top of my head.
So its quite large.