I thought it was alright. I'd rate it as a "good forgettable movie". If you enjoy seeing movies in the theater and don't mind seeing average movies there, then I'd recommend it. Otherwise I'd say it's a rental.
It was a little odd in that it felt like a mix of drama, comedy and action. I felt there were a some very one dimensional characters. The one thing that blomkamp always gets right is the action scenes and this was no exception, but I felt they were few and far between. I thought Ninja and Yolandi from "Die Antwoord" were fairly good. Specifically Yolandi.
Out of D9, Elysium and Chappie, I'd personally put Chappie as the weakest. But it is also a different genre so it's hard to rate like that.
I wouldn't recommend it, but it wasn't "bad". I'd say it's about a 7.3/10