Hmmm. Well, it's your loss if you don't try the new Steam. It works quite well, and is far far more sophisticated than any other tools that game makers have ever provided. Not having people cheating is good enough of a reason, before you get to the buddy lists, server browser, automatic patching, and the rest. And well, if you want to play any current or future Valve games, it's going to be required.
People might talk a good bit about not wanting to play HL2 or the rest, but I'll bet anything that most of it is just talk. You'll play. Oh yes, you'll play...
What's don't you like about Aliens, Wazooty?