Ive never had any troubles with the ATI opengl drivers.
Do you run a lot of different OpenGL apps & games? Please don't forget that most of the current fullprice games using OpenGL actually use the very same OpenGL engine: ID's Quake3 engine. ATI tuned their OpenGL driver so it runs this engine well. But nothing more.
Some fullprice games which aren't DX only have got an option to use the OpenGL or DX API but tend to set DX as default because of OpenGL driver problems (I would think ATI ones, not Nvidia ones). :-(
If you look around in this forum, you'll notice many ATI users with very different ATI models have a lot of OpenGL problems. For example two of the forum's top "projects" (Wurm and Megacorps) don't run properly on ATI hardware, at least not on mine.
I've seen ATI carded PCs which can't run Alienflux at all, some with trouble. On some of these boxes the very (!) newest ATI driver fixed the problem, on others it didn't. My own hobby Jogl and Xith project run fine on all
Nvidia carded PCs I've tested with, but just on some
ATI carded PCs, which is a pain.
Even Carmack stated during his Doom3 development that Nvidia's OpenGL drivers have got gold status for him, but no other drivers.
They have always given me a more crisp image than nVidia's. This is very noticable when you run a Vertex Program Cartoon shader at low res (640x480).
Well Hardware is another issue. Personally I like ATI hardware (and I use such a card for my home PC), but their OpenGL drivers just aren't OK, and in case this won't change I'll never again buy an ATI card.
But it is good to hear that they are improving it. It wouldn't hurt anyone, and it would certinetly gain a few loyal customers.
Well I'm going to believe it when I see it. ATI is known to be M$' DX friend so actually I don't really think they care OpenGL seriously (there have been comments floating around the Net from ATI driver developers who stated that in their opinion OpenGL was a very bad thing - so who wonders if such people won't care if their OpenGL hacks do a good job?), etc. It's just now that Doom3 has arrived ATI have got some public relation problems. I hope we'll see tons of good games using the new ID Doom3 engine because it'll help OpenGL and all OpenGL users!
PS: Don't get me wrong - I am no Nvidia apologet.