I used that before, but I am not a big fan because it doesn't really show which parts consume the most time.
Often parts that take the most time were not shown in the analysis.
Not sure if I will have the time for that, but I usually compare by timing it myself.
In my experience, that devel tool couldn't estimate the correct time when there is a loop or when 'fast' code is run many times (it still gave 0)