I have the clear version for my 15".
It runs probably 1-2 C hotter than normal. The plastic wrapped around the aluminum obviously retains some heat, not just CPU/GPU, but HDD and SuperDrive heat (where there are no slits in the plastic).
Other than that, i find the MBP much easier to grip with the case than without. Screen tilt decrease resulting from the plastic in between is negligible. I wish build quality were better, especially for a product with an MSRP of 50 dollars. (got mine for 34 shipped from ebay). Looks like speck removed part of the mold for the "updated" c2d version. They didnt take the time to make individual ports which i thought was half-a**ed.
but overall, the peace of mind that my computer for the most pat is protected form scratches is worth it. I can have it on my lap and not have to worry about my belt buckle or my keys scratching the bottom case. The rubber feet on the case give the MBP a death grip on the table, and i have to lift the mbp up and reposition it (also good cause i'm paranoid about those thin feet wearing out on the MBP). the MBP with the case fits no problem in my marware sportfolio.
