I had the really annoying sleep problem... and 5.3 seemed to fix it for me. I haven't had problems with it since. I can put it to sleep, unplug stuff, do whatever, and it doesn't wake with a dark screen. The only wrinkle is that I have lidwake turned off so I have to hit a key to wake it, and if I unplug or plug in any USB or the power cord... it wakes as soon as I open the lid. But at least it doesn't get stuck in the dark screen or "screensaver running in blackout mode" like it used to! The odd time it seems to wake up twice (have to enter password twice to get it awake), but hey - it works!
Hopefully .4 doesn't wreck it again... (.1 and .2 kept wrecking things...)