Even i have used R in the past for my thesis. My statistician was using S-plus to do magical things that the hospitals SPSS definitely could not do.
However, S-plus was not available to us non-statisticians.
As a complete non-programmer, mediocre statistician, i was able to reproduce en build upon his examples in R.
But what i truly missed was a usable GUI. there were some, and i tried them all at the time, but none were able to do more than the basics. For someone using R daily, a GUI will be more trouble and limited. But for someone like me, a well developed GUI like S-Plus had at the time would have bee more than welcome.
Seeing the headline R 3.0.0, the first thing i was looking for: did they include a GUI by default???