I used Kaplan to prepare for New York. I thought the MBE stuff (PMBR) was pretty good, and the MBE lectures were relatively easy to sit through. I attended a BarBri weekend "bootcamp" hosted at my school. The platform seemed almost identical to Kaplan, but I don't have any actual experience with BarBri.
You can get a feel for the Kaplan platform from their youtube page:
http://www.youtube.com/user/KaplanBarRe ... ture=watch
Several of my friends used BarBri for the main course material, and Kaplan PMBR (not the full bar prep course) to review MBE questions. I understand that there are stylistic differences between the BarBri and Kaplan MBE questions, and several of my friends advised me that they thought the mixture of questions helped them on the actual MBE.
I understand that relativity recently, the founder of PMBR (Robert Feinberg) left Kaplan for BarBri. Perhaps that may have an influence on both companies on their MBE questions?