The fact that it tracks every aspect of my DB, how long things take to run; what queries are taking much longer than others -- even if they're not running at all!The UI/UX could be improved (but this may just mean getting used ot).
We use JProf in combination with our own scripts where we can write functions or SQL using its API - very useful when working over remote computers etc as there's no need tp install anything locally which might create problems elsewhere down stream from your localโฆ