The superslim does feel a bit flimsy and the blu-ray drive can be noisy as hell, especially on GTA V. The Sony warranty sheet that came with mine offers 1 year replace with new, then an additional 2 years swap for recon / repair.
Only get the 12gb if you have a spare 2.5" hdd kicking about, you'll need a mounting kit but they're easy enough to get hold of from the rainforest place or auction sites. Without an hdd upgrade the GTA install alone will fill up most of the 9GB available to the user, preventing any other games being installed alongside.
I got a 12gb Superslim from OcUK with God of War ascension thrown in (approx £120 inc next-day delivery) and grabbed a mounting kit from the rainforest place for £8 as my aging Fat PS3 had a YLOD and failed a reballing attempt. I'd already upgraded that to 500gb though so just swapped the drive over.