The problem is that the R51 was rushed into production so that they could introduce it at Shot Show. It wasn't ready for prime time yet. There is additional work that needs to be done. The company for which I work sells them, and NONE of us recommend them at this time. While it has a very nice sight picture, feels pretty good in the hand, and has one of the easier slides to operate (which is good, because it is being marketed specifically to women, and really stiff slides are the chief issue that keeps women from buying autos), the grip safety just feels cheap, the slide action is really gritty, getting it fully into battery is an issue, and almost everyone says that, compared to other 9mm autos this size, the recoil is VERY difficult to control - making it very difficult to keep on target. That doesn't even take into account all the rest of the issues owners are having.
The R51 has the potential to be a very nice gun, but Remington has a TON of work to do to make it so. I would give them another 6 months to a year before I would even considered buying one.