I was a beta tester in ROF. I would try to sum up cons and pros.

pros:
- best FM up to date; DM too to some extent
- features newer seen before in a sim (like realistic sun glare, moving clouds with moving cloud shadows; you can extinguish engine fire with fast dive etc etc)
- realistic weather with impact on FM
- nice graphics
- very detailed cockpits and plane models
- friendly community (they have "fights too", thats how it is with simmers, but generally friendly and at hand if needed)
- devs listen their customers however on some issues they are stubborn (some of them spec.) and will not change a thing...

cons:
- optimisation/graphics problems (on some systems (even on latest HW) some users experience flashy textures (me included) when flying over no mans land - this is due to "optimisation" as explained from devs; on some systems stutters often, flickering landscape on some areas etc etc)...it was explained that its "hardcoded" and will not be changed.....this started to happen after introducing cloud shadows...
- ackward and non intuitive mission editor
- still no career mode
- small multiplayer community (50 players at best at weekends; and that is on most popular server)
- FM issues on some planes still not fixed (N17 roll rate, se5a engine etc..)
- limitations regarding number of units (planes and ground units) on server...very limited for smooth gameplay
- lack of AA on landscape resulting in heavy shimmering for most players....
- DM issues; some planes still able to fly with whole wings ripped off (I know it was possible for a short period of time but in the sim you can fly longer....I know in modern era there were planes with very small wings which could fly, but they were constructed to fly like that....WW1 wingless plane couldnt for sure...)
- DOT system....well il2 view system isnt much better but it is better than in ROF...in ROF you need to apply max zoom to see planes at greater distances; if you unzoom they disappear....like we have a binoculars sticked onto our faces...and usually its painful to use super zoom all the time to scan the skies)

All in all its a great sim (regarding feeling in flight) but have some serious optimisation issues + ackward viewing system).....