Even if all review queues are "converted", I'd propose to have a way accessing the "old-style" review tools. With the new review-beta, one gets shown only 1 question at a time and is forced to decide upon this. There's no way to postpone ones decision on a more difficult question. This may lead to "trigger-happiness", where in this case one would just push any button to "see something more useful" (in ones own opinion, of course).
I watched myself working with both systems in parallel and found: I like the new system when it comes to "vote for closure" (decide whether something is a dupe, off-topic, whatever). Here I either have an opinion or not (the latter mostly when I'm not familiar with the given topic). But speaking about quality, it gets harder -- and I find myself reverting to the "old-style" review system, where I can pick items freely, while still being able to check on the other ones later.
It would be great to have a link to the old review system available, say, at the bottom of the "Help improve the site" box. This way one can switch between systems and see which feels more comfortable. Which would also help avoiding above mentioned "trigger-happiness".
EDIT: To underline what I mean, let me quote from another question here: As it stands now, I rarely touch the edit queue unless I'm really bored because I don't want to have to wade through a ton of questions that I can't necessarily help with. This describes quite well my feelings: For certain review queues I feel I could be much more helpful using the old system ;)