There is no doubt about it, Rega are giving the vinyl fans some really good turntables. Each new model they bring out is an improvement on the older model it replaces, however, I suspect the improvements are not quite as dramatic as some would say, I think Rega work on the 'evolution' principle rather than the revolution.
I have an original early 80's Planar 3 with RB300 arm, its had a few 'tweaks' over the years and it sounds great, I would be more inclined to move up a step if I was to replace my Planar 3 rather than just get another up dated Rega deck. So my upgrade path would be some thing like a Clear Audio or Michell. If I was starting out then yes, the new Planar 3 would get my attention.