Here is my own personal review of both IL-2 and IL-2:Pacific Fighters [PF].
1. Because PF is part of the IL-2 series and can be installed together with along with IL-2: Forgotten Battles [FB], the graphics are the same in my opinion and they are impressive.*
2. Stall characteristics are apparently overdone. You'll notice that you'll be stalling like heck whenever you do a tight turn or whenever your not using the rudder properly.
3. There is no autorudder in the IL-2 series so you'll notice that you're required to use the rudder manually to avoid the stalls.
4. Online sessions are incredibly stable, although you will run into some occassional players who don't have anything more than a 56k connection. Speaking of online sessions, Gamespy hosts the main servers, but you can also use a direct IP connection [if I remember correctly].
5. The only difference between the entire IL2 series and CFS series is that the scenery doesn't cover the entire globe. In fact, you're restricted to a rectangular area and the boundaries are obviouse.
6. You'll notice that you don't have the option to skip certain parts of a flight and therefore you're only options are either to fly along or to use warp. Please note that the warp feature is useless during online play.
7. Warning, whenever you play online, be on the look out for any German planes out there looking to shoot you down. Chances are it's probably piloted by actual Germans [cough]Bjorn[/cough] who seem to have a good understanding on how to handle those unstable birds.

8. Patches are available to download, but the installation process of these patches are time consuming and you beter have a good connection and time as the downloads are somewhat large in nature.
*Note: If you want to install PF along with IL-2, you also need to have FB installed as well. Here is a list of available installation options:
1. IL-2+FB+AEP**+PF
2. IL-2+FB+AEP
3. IL-2+FB
Notice that each version is installed in the order in which they were released to the public.
**AEP stands for Ace Expansion Pack. It only expands the FB verison of the IL-2 series.