Good high-key work - thank god you haven't gone for the 'perfectly' white background which is so annoying to the eye. I can't say I like the composition of subject very much - though it does have a strong element of recession to it, I think it has become too complicated; my temptation would be to have lined them up more, use a stronger diagonal composition ... but I'm not certain that would work any better :-) A pretty common subject approach too.
Like the idea a lot, but I think I would've made it a wider, landscape formatted shot and maybe have the newest in focus. Hard to say until you see different variations. Good job though!