I actually think it looks plastic-y. Probably this is due to the gray bit around the keyboard. More subliminally still, the lines just aren't as good as the 15" PowerBook, in the same way that one can look at clothes and tell when they're just not cut right.
Or it could just be that I like seeing my TiBook every time I use it.
On a slightly off-topic but related vein, the other thing is that no matter how well it looks, it's got to deliver that fit and finish in the user experience or it's not worth taking home from the store.
I've a friend with a souped-up Dell that probably cost half what I paid for the PowerBook, but every time I use it the awful trackpad makes me want to scream! First it doesn't realize that I'm touching it, and then the mouse pointer doesn't follow my finger properly after it does appear. Dunno if that's Win XP, her machine, or just Dells in general, but I'm tempted to wonder how she gets anything done!