User blog comment:The Milkman/Mass Effect in Retrospect/@comment-3228423-20130417021124/@comment-3228423-20130417121405

Well aside from expanding on Cerberus, ME2 expands on a lot of other things:

1. Showing that the Reapers have gained an interest in humanity as well as revealing what truly happened to the Protheans, and showing what will happen should Shepard fail to stop them. 2. Shows that the asari are more than a bunch of strippers and that they have (extremely dark) secrets of their own. 3. That the geth aren't a race of evil machines that want to destroy organics, and that finding a way for them to make peace between them and the quarians is actually possible. 4. Krogan culture and the struggles Wrex is having to prove that they aren't all mindless savages that should continue to suffer. 5. Introducing the drell And etc