Funny that the "two blue" trace color topic has surfaced again. That's my Number One complaint about my Rigol DS4000 series scope.
That is quite interesting; I don't really have a problem with the two shades of blue but I understand your reasons for complaint - the colors are not very dissimilar.
To me the interface itself is so personal that it is impossible to quantify. The Tektronix interface of an old TDS3054 (B or C, I don't recall) that I used to work with was quite alright for my taste, with the only pet peeve being the large surrouding menu areas that prevented the graticule from filling the entire (already small) screen. Also, the cursor and DC offset cursors were not terribly fast and got worse as math/FFT was applied, but I was ok with that - as @Gandalf_Sr and @Fungus have said, it didn't block me from doing anything.
A bit later I got my old Rigol DS1102E which had a similar easiness of use and responsiveness, thus I was quite comfortable with it. Not knowing better, I started using a "washing machine" Windows 2000-based TDS7104 that had a seriously terrible interface and responsiveness. I would take my Rigol any day.
A few years later I got a DS4014 and, despite four channels, it has independent controls and the row of buttons on the left side of the screen are really handy for me - I use measurements a lot and don't have a problem with the fonts themselves. Its menus and overall UI and responsiveness are somewhat similar to the old TDS3054 but the reviews around the internet say its responsiveness is crap. After playing with HPAKs DSOX1000, DSOX3000 and DSOX4000 I can tell why - they are the kings of buttery and smooth controls. However, these models don't have the left row of buttons and the menus are less obvious to me (perhaps a matter of familiarity). The worst aspect of the two lower range HPAK models, however, is the rectangular graticule - they fit the same ten divisions but on a wide screen (the DSOX4000 has a 4:3 screen). The DS4014 has 14 square divisions on the wide screen.
I also got to play with the Lecroy (forgot now which model) but it was equally smooth and a really capable oscilloscope - that would be a brand I would heavily consider if I had the dough. The more moderns Tek MDO 3 and 4 had a terrible UI and responsiveness. I never used a R&S but the reviews tell it is a great product.
All this to show the umbrella statement that Rigol UI is crap may be overblown by one's past experiences.