Until a few months ago...
My life with my Macbook Pro 17" 2.16 was pure bliss until around Halloween 2007 when the hard drive catastrophically failed. Luckily I had actually done a backup for some inexplicable reason (angel on my shoulder?), and upgraded to a 200 GB 7200 rpm Hitachi from the stock Seagate 100GB 7200 rpm without too much blood and treasure. Leopard had just come out, and I had that installed as long as I was starting from scratch anyway.
For some reason, especially since around Christmas, my machine has begun freezing up totally a few times a week, sometimes a few times a day. I've read elsewhere on this site about others complaining about keyboard lockups and such, but my mouse and EVERYTHING simply stops cold and I have to hard-boot. I tried waiting, I've tried using Disk Utility, Disk Warrior, zapping the PRAM, etc. One other thread here talks about the same problem and they used TechTool Pro without results, so I haven't bothered with that. I've read the logs and can't find any telling problem.
The only warning I get--if you can call it that--is that I start seeing graphics artifacts on the screen. Sometimes I see transparent blue swooshes (like the genie effect for the dock, but frozen in place), or a TV-static like line across the screen at some random place.
The only caveat I have here is that I push this thing hard. I use a lot of processor intensive apps, and even when I'm not personally running it, I have BOINC running, so my processor usually runs at 100% 24/7/365. That said, the G5 does the same thing, and so did the G3 I had for years--all without a problem. When I bought a 17" laptop, portability was not my primary attribute--it was the power to run the stuff I need to run, so I expect it to run hard.
I never had this problem before, and I've had this computer since they came out in the spring of 06. I used to have uptimes in the range of WEEKS (and only then because it's a portable and I took it somewhere). My G5 has uptimes of MONTHS and never locks up or crashes. Until this problem started happening, this thing absolutely ROCKED and I don't want to use anything else.