Got into the closed beta, too (thanks to Mopskind) and while I´m usually not a big fan of the Pacific War, I´ve got to say that it´s quite a nice mod, sorry, expansion pack.
The atmosphere is pretty good, sounds are really nice and it has its own unique features that make RS feel different than RO2.
Fighting in dense jungles is a new challenge, that takes some time to deal with. And when I was bayonetted by a Japanese who charged me out of a bush only a metre away I felt pretty scared! Same goes for the flamethrower which is a pretty dreadful weapon tha results in some really disturbing sound effects...
Unfortunately I can´t say much about graphics, since I´m at my parents house this weekend and can only play the game on my 3 year old laptop.
There are some minor things that annoy me though, most of which seems to come from RO2. So far I don´t really feel like spending money on the game, mainly because last months bills habe been a bit high, but fortunately the beta will run for some time and maybe the game will become even better than it already is.