I've been playing for about 3-4 months now, it's a great mod, i'd put it second best mod in Half-Life (DoD is my first love

).
You can get accessories for your guns like laser sight, scopes, silencers etc.
You can dive, use kung fu, throwing knives.
You can get "power ups" which lets you use Slow Time (Makes you move slower, but looks really cool when you use it with a dive) Stop Time (Stops time, you can move a little and fire a little) and other stuff such as the Hulk Jump (You jump REALLY high and if you are skilled enough, REALLY far, i jumped from one building to another on this map, it looked so damned cool).
All in all, it's a great mod, i'd suggest checking it out if you haven't done so already

.