You can still give a 3/5. For the amount of weight it had in determining the star rating of a video you might as well not vote. Not voting is the equivelant of giving one up and one down vote, or a 3/5. The only place you miss out now is 2/5 and 4/5.
It would be trivial to write a greasemonkey script that converted up/down votes to stars. It wouldn't be quite as accurate as the old system since 2, 3, and 4 ratings wouldn't be counted, but those votes don't matter as much anyway, (a) they are weighted less than 1 and 5s and (b) if you actually used these votes you are in a very small minority, most people used 1 and 5.
As for the layout, I've already stated my opinion. As far as video sites go the only thing youtube has going for it is its popularity. Almost every other site on the web looks better and runs faster. Youtube has come a long way especially with the site redesign but its got a ways to go.