Yes i don't get you wrong, here is my opinion:
1-it messed my ping, before i played il-2 for hours and never got a timeout message, but when installed the PF the multiplayer became horribly unstable, after 1 min approx. i always got a red bar and a message kicked due timeout or something like that.
2-The merged and stand alone version, the community was devided by this fact. some stayed stand alone and some merged. And the programmers didnt do nothing to atleast try to make the both versions compatible for online play.
3-The terrain graphics, especially pacific ocean waters. Don't get me wrong i have a pretty decent computer for this game. But the graphics just sucked for me ( CFS3 on the other hand i play almost on max and never get a slight lag or timeout) But pacific fighter its a complete different story.
4-The flight models became horribly stacked to american side( russian and german planes were left behind) You can read alot of comments o their official site ( been there but decided to leave because the community became nothing but whiners)

So this is pretty much my story . Sorry for few examples but its been 6 months since i last played IL-2 series so i came with this from the buttom of my head.

Don't start this thread, it'll lead to wars