Hey guys,
I believe that this mod greatly increases the realism and fun aspects of ARMA2, greater than what operation arrowhead brings to the game. If you are willing, this is a tutorial on how to install ACE2 into your ARMA2 Combined Operations game, or any other mod listed in the six updater.
First of all, make sure you have ARMA2 combined operations. If you dont, get operation arrowhead, its better.
Secondly, download the six updater suite from this link:
http://www.six-updater.net/p/download.html. Download the latest stable version.
After installing and running the six updater suite, it should automatically ask you to locate your operation arrowhead folder, which you should locate within the updater if it doesnt already do so.
This youtube video further explains this:
Note: dont worry about launching the game through six updater, its too complicated, and make sure you download the CBA mod from the six updater.
After this step, download this launcher for arma2 from either here:
http://www.armaholic.com/page.php?id=8241&a=dl or
http://files.tom4897.info/Bohemia_Interactive/arma_2/misc_utilities/ArmA2Launcher-1_4_0_0.zip.
Another youtube video to further illustrate how to use the launcher.
Note: when launching ARMA2 with the launcher, make sure you have all files related to ACE (ace_sx, ace_sm, ace_usnavy e.t.c.) and the CBA mod selected to launch in the right hand column.
Anyway, if you have any problems with installing the mods or ARMA2 in general, send me a PM or ask me on TS.

Here is yet another video showing off some of ace's features.
EDIT: note the lack of rubber-banding of the AI



I hope this tutorial was useful!
Thanks for reading,
Mandy