Best Reviewer is a great AdSense Revenue Sharing website! I use it to power backlink my hubs and websites. Yes it is 100 % AdSense sharing website.
If some one referred you to them though then you do not get all of the AdSense Ad space on the page. So if there are 4 ads on the page, you will split them with the person who referred you to Best Reviewer. Also if your not a paying member I do believe you do not get all of the ad space.
In the end it does not matter because your ads are at the top in the best place for getting AdSense clicks. I personally love the website and it does make me some money with Google AdSense. As Best Reviewer is one of those rare websites that give you 100% of the revenue. However you do not get all of the impression income. That is little income anyway, we would all rather just get 100 percent off the click, which is how Best Reviewer works. SheToldMe is run by the same person as well, and is another good website for social bookmarking / backlinking. For more tips you should check out some of my hubs on the topic. Hope this answers your question.