It does cost money, though (for the record). When I read Doc's counter-post I thought he was refuting the need to pay. That's not the case, but it is still an Unreal-based product, just one of the increasing number of games that Steam will distribute regardless of any relationship to the Source engine.
Given the quality of the mod, this one might well be worth paying for. I've not played for a little while, but my memory of the sniper scope, for example, is as one of the best I've ever used in a FPS.