I always check up this type of forums before I purchase my computer. So far, there are so many negative comments on various forums, even though that is not a scientific way to measure the workmanship of the machines.
I did not buy iBook when I was ready many comments on logic board problems; but, I bought the last rev iBook as I detected more praise on its virtues.
I checked up MB at an Apple Store and a CompUSA store. I noticed the display machines exhibited tendency to show more beach-balls than I recall with iBook and PowerBook. Maybe some customers messed up the machines; but, I have not seen the same conditions with iBook/PB when I was checking up the machines at the store.
I admit new MBPs look nice; but, I have decided to wait till next year when more Universal Binary software becomes available. I hope Apple will learn a lot from "beta testers (i.e.. early adopters)" to fine-tune their hardware. After that stage is done, I think MB and MBP are ready for a prime time.