how about the harddrive and is there "any" common defects that i should be aware of about the new MBP ?
Hard drive: I got a Seagate Momentus 500GB that seemed to work fine but was quite loud, and then it failed after about two weeks. I now have a Western Digital Scorpio Blue 500GB and it is very quiet and performs well.
Defects: Hard to say how common they are, but I've encountered most of them already.
My first machine had a dead pixel (unacceptable to me), severe backlight bleed (9C84 screen) and extremely crooked keys.
Second machine had no dead pixels but even worse backlight bleed (9C84). The keys were a little crooked but I didn't mind. The machine went back because of the backlight, though.
Third machine has a beautiful screen (9C84) but the SuperDrive completely failed 48 hours after purchase. Not wanting to risk other defects with a replacement computer, I opted to have the drive repaired. Soon after, the cooling fans started the rattling/grinding noise that some have encountered. Had the fans repaired. Then the LCD started flickering when running on the 9400M at any brightness less than 50%, so it's in the shop for a logic board replacement. If that doesn't end my problems with it, I'll be asking Apple for a replacement machine regardless of the fact that I'm well outside the usual exchange period.
Try not to let this scare you. I just have, and always have had, the worst luck with MacBook Pros. No other Mac I've owned has ever had a problem, but as for MacBook Pros I have been through a LOT of them since 2006.