Brilliant expansion - expands on the infantry combat [best stuff in BF2]
It is easier to destroy armor and there is less of it. The grappling hook and zipline [which I was very skeptical of] open up some new strategies and because they take some time to operate, doesn't result in people climbing and zinging all over the map. Furthermore, the tear gas and flashbangs make for some fun offensive and defensive strategies. Because access to new items is based on class, the expansion serves in making it more important to have a balanced squad to be really effective. If you have one guy with a hook, one with a zipline, you can move the whole squad. The night levels with nightvision are well constructed, and balance light and dark areas well. The new vehicles fit the theme and don't unbalance gameplay. For the suicide bombers out there, the new ATVs are real fun to load up with C4 and drive around.
It is $30, but for the number of hours it will afford in terms of replayability it is well worth it. Furthermore, you can use newly unlocked weapons in original BF2 if you get the expansion, which is a nice plus. I always felt that the infantry vs. infantry was the most fun in BF2 and was annoyed with how dominant and important vehicles are in some maps. The expansion really puts the emphasis on well balanced cohesive infantry squads.
The best FPS on any platform just got better and more addictive. Well done.