Outdated? It's anything but outdated. It's getting constant updates with a whole new lighting system and cloth physics on the way with DotA2. Don't pull out the stuff excuse with "it can't handle open areas!" because that isn't what it's meant for. It's meant for smaller, less open maps like in TF2 and CS.
the reason source is outdated is because it's only good at said closed areas, which any other engine can do.
it takes forever for source to bake in (static) lighting, it takes forever to compile, the hammer editor still has non-functioning entities and a layout that hasn't changed much in over a decade, etc. the good points for source is: it's easy to mod, and scales easily. both of which unreal engine can do.
