Of course I'm going to buy it. However, this time around I think I might stick to the core books only. Why? Two reasons:
1. I have a mountain of 3E and 3.5 materials that I've been collecting and using for the last seven years, and I expected to have at least another three years before I had to start the endless buying loop all over again. Heck, I just picked up Spell Compendium last month. Rules Compendium is coming, along with a bunch of other 3.5 books, and they're announcing 4E? I don't like that. I know people have to eat, but I still don't like that.
2. The splatbook overload has lead to some problems at the table. Namely the rhino's rush spell in Spell Compendium combined with a half-orc ranger, power attack, a greataxe, improved favored enemy and combat brute from Complete Warrior, and great leap from Complete Adventurer. It's as if designers aren't even considering other books. I'm seriously considering only sticking to the core books, both to save me some money and keep things in line at the table.
I might not want to buy a fourth Player's Handbook, but I will so as to stay on board with modules and such, but I'm tired of having to buy all my books again every 7-8 years.