The previous review stats had more options which you could complete on a post than the new review beta seems to provide: flagging, voting, and commenting. While I'm not sure if any of these three will be present in the other review tasks yet to be created, I'm curious as to what you're planning to do with the stats that users have built up in the old system when you decide it's time to switch to the new one.
Will the stats somehow be combined, or are stats going to be completely reset? Resetting them won't hurt anyone who hasn't really reviewed anything yet or already has the Reviewer badge, but those who have been working towards it and might be close, that might be a bit of a stab in the heart. I personally enjoyed reviewing just because it was something to do; my goal was to get my numbers as high as possible. Simple right? But this leaves me in a bit of a grey zone. Do I continue reviewing like normal? Should I focus on one thing over another? I get that the premise behind it is helping the community, but it's a bit demotivating not knowing what will happen with the stats I'm building in the future.
As well, with all the changes going on with what you can actually do in the review panel, will the badge be changing as well? There are a lot fewer actions you can complete, and we're not exactly sure how the new system even tracks things. Presumably any action other than "Not Sure" would count as an "action" on the post, and every one you at least click a button for will increment your "reviewed" count. Is this intentional to encourage more of a "clean-up" behavior through reviewing rather than just letting people vote on things as actions, or will the badge be modified to compensate for the limitations of the new tasks?
In case you're interested: