Just like BF1942, it is taking me time to dig deeper into the engine and see just what it can do. In bf1942's case it took me at least 3 years of tinkering with different code to learn how useful it could be to do such things as, 3d Ironsights, Animations, Distance Sounds, Random Soldier Uniforms, etc. But once I figured it out I was happy and made my own little miniature mods to satisfy my craving for such things. In BF2 i've spent long points of time working with code which I don't see featured in the Vanilla Version, to see if it does have effects on anything. One in particular is the Randomize Geometry code, which although I've had no success implementing it with soldiers yet, I hope to soon.
BF2 is good for a good many number of reasons, the first and most recognizable being that the Graphics Engine was updated, and allows for a much more diverse set of graphics techniques than BF1942, my personal favorite being Normal Maps. Its Animation system is far better as well, including a Camerabone, and unlinking the right hand from the weapon, to allow for both hands to be used in the Animation, instead of just the left one like in BF1942, which is a godsend to modders. Even though I don't like the tools for importing and exporting as much as I did bf1942's tools, they still get the job done.
BF2's map editor, as was mentioned above is a lot more useful than bf1942's was, while someone could get talented at the bf1942 editors and make some really amazing looking maps, the BF2 editor just allows a mapper so much freedom, with roads, undergrowth, overgrowth, the more detailed heightmap's and better texture painting, so that they can make visually stunning maps on a new par than bf1942.
BF2 also has ragdoll files which are fun to tinker with, and some very useful Soldier modification code which can increase a soldiers speed, how high he can jump, how slow or fast he crawls or crouchs, whether or not he can shoot while jumping or sprinting etc. And I find this great fun to mess around with when I'm making a single-player mod for myself.
While BF2 doesn't seem to support Serverside mods as openly as BF1942 did, it is possible, and I can expect to see some Normandy maps modded with extra vehicles in the future, and with Patch 1.5 it seems that some Hotfix problems are finally being resolved, so the future looks pretty bright for BF2, regardless of some of the beloved code that was removed between the 2 games.