I wouldn't say the R is an 'upgrade' as such from the GTI, just another model in the range.
Personally, I wouldn't buy an R. It would be a shed load more money for, on the face of it, the same car. Interior is pretty much identical with blue in place of red, and external panels are pretty much the same too.
If I could have got an R at the right price, I'd have probably bought it. I wouldn't get one now. My next car within the next 6 months will be an RS3.