I had my 855 for over a year with no problems and a month ago it started acting up. I was able to get a new one (refurbished) back from an RMA and all is good again.
In the time that the 855 was in for RMA i used a D-Link 635 which i must admit was a very nice router. The 655 is a step up from that one so i wouldn't upgrade unless your current router is damaged in some way that you cannot send it back for replacement or repair.