Uh... the UI has kind of a seasick greenish tint?
Seriously, there is a bunch of things that bother me about REAPER. I paid for it because I like it and to support the developers, but also because as a registered user my requests will hopefully carry a bit more weight. So it's not like it's a perfect DAW, it has numerous flaws (my top two complaints would be the crude midi CC lane editing and the lack of a native stereo panner).
Still, unlike most other commercial DAWs, things get done around here. Before you know it, feature X will be implemented and bug X will be fixed