And mitai(na/ni) is used much the same way as you.
意味は"格好良い"や"おいしい"や"美しい"という ような肯定的ことですが、英語のCOOLみたいな感じ だと思います。
In the affirmative, I think the meaning (talking about イケるとかイケてるという表現) of good appearance, delicious, and beautiful has the sense of "cool" in English.