i have the 15" 2.8ghz from late '08. considering how heavily i use it for motion graphics work, the hardware issues have been relatively minor and the repairs were quick and easy:
-after about a year the optical drive stopped being able to burn disks. took it in and they replaced it while i went for coffee.
-after 2 years, the battery started to bulge, took it in and they swapped me a new battery on the spot.
-the 9400m always had the screen flickering issues others have described, but i only use it occassionally and the 9600 has been perfect, so it never really bugged me at all.
i've had several larger headaches, but i'm quite certain they were software issues specifically related to snow leopard:
-after upgrading to snow leopard, wifi dropouts were frequent for about 6-8 months, even across several fresh reformats. but the issue resolved itself around 10.6.4
-after upgrading to snow leopard, ram management became a huge issue. the computer would regularly completely eat through the 4gb and slow to an absolute crawl. recently i bumped ram up to the unofficially supported limit of 6gb, and it's partially mitigated the problem. yet it was still annoying that 4gb never created slowdowns with similar usage patterns under leopard.