Sadly, this is not a rare situation but commonly with new Radeon hardware enablement it has become fairly common. When the support matures, the most common regressions tend to be incorrect rendering within OpenGL games (or games crashing), display problems, or memory management issues. For example, with R500 class cards when running Lightsmark, many of the textures were black during this test.
Lightsmark is not the only common OpenGL test case that has problems with Radeon Mesa / Gallium3D. VDrift, an open-source racing game that is OpenGL 2.1 compliant, has had problems with all generations of Radeon ASICs going back a number of months. Rather than rendering smoke and some other effects, the textures are simply white.
But that is not all in terms of problems. When it came to testing the Radeon HD 3650, Radeon HD 2900XT, and Radeon HD 2600PRO graphics cards, there were GPU lock-ups here too. It was a near continuous stream of lock-ups for these graphics cards. It did not happen for all of the HD 2000/3000 series graphics cards, but among the ones tested, the HD 2400PRO, HD 2600PRO, HD 2900XT, and HD 3650 were affected. This issue did not affect the Radeon HD 3850. There were also other separate issues with the Radeon X800XL. The only Catalyst driver hardware issues experienced were lock-ups with the Radeon HD 2600PRO and Radeon HD 4670 graphics cards, but this didn't impact the other R600/R700 class hardware and is a regression as both cards did work previously with this binary blob.