The 15" doesn't feel flimsy exactly, but it doesn't seem as robust. I feel I have to take care of it in a way that the 12" didn't need.
Is it the build quality you are worried about or scratching it?
The latter would be indicative of a 'new' feeling as Mindflux suggested. I remember I had that same worry when I got my 12" PB new. I bought a
PowerBook Sleeve and that solved it nicely without adding bulk.
But if it is the build quality you're worried about then of course that's another matter.
What prevented me from upgrading so far is the lack of alternatives.
I'm a bit sick of people suggesting the MacBook Air as a replacement.
Are these guys aware that the MBA is almost 2 inches (!) wider? That's almost 20% wider.
And it's about a third of an inch deeper.
Yes, it's thinner and lighter. But I care more about the footprint. And on that front the MBA is a
behemoth compared to the 12" PowerBook.
My only hope is that once the much fabled Resolution Independence arrives bundled with smaller Montevina motherboards that Apple will introduce a 150dpi 12" MacBook Pro. At 150dpi we get 1440x1080 resolution.
With 200dpi (as the iPod nano) we would even get 1920x1400 resolution. BluRay HD anyone?
I'd be first in line!
Until then, I'm not so sure... all available options seem a bad compromise.