This goes for everything - GPU / graphics cards, CPU, software, and even shares.
I recently got my first AMD graphics card and found it to be extremely bad in quality - both the hardware itself as well as the drivers.
My first card was from MSY (VIC Australia) - it was a Gigabyte 4350 (AMD / ATI card). Plug it in to my old machine which was sidelined recently due to an upgrade, but had been running ECS nVidia 9600, I found that the GDDR2 chips are defective. In fact, booting into Vista caused the graphics card to lock-up entirely. After some investigations, I discovered that there are a few frequencies that the card chooses depending on the state of the card - it boots up with a 200MHz GDDR2 RAM frequency (400MHz effective) and runs 3D (load) with a 500MHz (max default) frequency.
Keep in mind that this is the default frequencies (read: NON-OC'ed) from Gigabyte. Just to get a closure and confirm that it is in fact defective RAM as I had suspected, I flashed the video card BIOS with one that runs the RAM at a lower speed and found that it worked. The maximum speed I could get it to run at was 300MHz - a far cry from the advertised 500MHz (1000MHz effective)! Heck, 300MHz? My OLD machine is running 800MHz DDR2 (1600MHz effective). And to put that into perspective, my nVidia 9600GT works perfectly with an overclocked GDDR2 at 1200MHz (2400MHz effective)! Gigabyte and AMD - shame on you!
I'd also avoid Gigabyte at all costs. So far I've owned 5 Gigabyte motherboards - none of which I could go to the shop, purchase it, and plonk in a CPU and install OS. Gigabyte = troublesome. I'd have to return it and get it exchanged for a new one. It's not the 2nd board that'll work but the 3rd! Most won't even get past POST. Apparently, it's no different with a graphics card.
Back to the graphics card issue - this time the shop ran out of the graphics card - so I got to the 2nd, and that did not work either. Eventually we settled for a refund. I immediately drop by Centrecom and got myself an Asus 4350. Dropping it into my system and it immediately worked - 3DMark06 ran flawlessly (discounting the performance of course).
Then, I decided to watch some blu-ray contents and to my surprise, it stuttered like mad. Why? Because it's using my old CPU to decode in software - no UVD! Keep in mind this is with Media Player Classic - HC, which used to accelerate blu-ray with my nVidia 9600GT (which was running a BETA driver, as opposed to the AMD 4350 which was running the official Catalyst 9.1).
After spending days reinstalling Windows and drivers, I still had no luck. Eventually, I stumbled upon AMD's own forum while looking for solutions and found that people have been complaining about the same thing - Catalyst 9.1 broke all DXVA support in Windows XP! I immediately did a driver feedback via their website and told them the issue.
A month later, Catalyst 9.2 was released. Still broken!
I bought this card for the sole purpose of accelerating HD contents - if the card can't do it, then stop advertising it! At least in Australia, the law protects consumers in this regard - we can return it if we find that it does not do what it's advertised to. I'm sure in US consumers have no rights whatsoever and get lied to with false advertisements.
My advice, stick with Intel and nVidia. Heck, even Intel's G45 integrated gfx would've been a LOT better - yes there're some issues with 24Hz playback (1920x1080p 24Hz that is, and not all TVs support that) but for all other modes, it accelerates HD contents flawlessly, just as advertised.
But, with that said, I'd like people (read fanboys) to continue buying AMD just to keep Intel and nVidia in check (quality, performance and price). :-)