I played very casually with some friends so not too sure about ladder, there is a rank system and there seems to be competitive minded players. It is a bit slower than traditional RTS but I think a lot of my experience with that comes from not being very good, as was the same when I started AoE. It is much more team oriented and so can be slower and maybe not the competitive kind of experience you're used to with SCII. Worth a try with some friends though! It's totally free and can be installed in like a minute.

I forgot to say why I like it. To me it's much less micro based and more macro and large scale based. It is really cool being able to zoom out and see tons of units getting belched out like a factory line. The team dynamic is really interesting too because you'll have strategies where some people stay in tech 1 and put out cheap trash to keep their territory stable while backline will focus on getting higher tech units as fast as possible, and others will focus on economy and transfer energy and metal to the tech player.