It's very good. Different from the comics. It's got the same shape, but some things are brought in from earlier than the comics, some plotlines are changed up to keep the focus more on the main characters, and some of the characters are tweaked slightly. It's all recognizable but different enough that even if I remembered the comic story in full before watching, I would have been surprised.
And the guy that's playing Number Five is fantastic. Making him a few years older (in the comics I think he's ten years old, here he's thirteen) was definitely the right call.
I do hope we get season two soon, and that we get Number Five's gazelle speech.
We're two episodes in. Someone suggested the comics to me right around the time they first announced that they were looking into doing a series, so I consciously chose to avoid all information about it until after watching the show. It's so rare to see a piece of geek media where I don't know spoilers, or aren't spending my time deciding if I approve of the changes they made.
And Mary J. Blige needs to act in more stuff. For serious.