It's pretty, but I don't think it's an improvement. The problem with the highly visible login boxes is that they distract from the other actions available - wat

It's pretty, but I don't think it's an improvement. The problem with the highly visible login boxes is that they distract from the other actions available - watch a video and download the client - which are exactly what you want the first-time visitors to be doing. It should be very clear for first-time visitors what to do. Existing users already know what to do, so it is fine for their action (login) to be tucked away in the corner. Dropbox doesn't want first-time users to decide what (if anything) they should be doing with those login boxes. But then again, the true test is of the A/B variety!