I wouldn't consider it Maeda-sensei's best work. For me personally, I found it quite an average watch for the usual "Key" standard. Interesting concept but I don't think 13 episodes truly fleshed out it's true potential. Use the 3-EPS or drop formula and see how it goes for you ¯\(ツ)/¯
I second @SAHO, not Maeda's best but not bad either. Good concept which could've been developed better, especially given that I found his Angel Beats fantastic over a similar twelve episode run.From here on we don't know what will be on AL's release radar I guess. I have been wondering about Charlotte though, is it any good?