Yeah, god choice has something to do with it. Also how much your build/run crave inventory space. Also, it's probably a good idea to hang onto it until you've seen the subdungeon, just in case. The monster zoo secret subdungeon is about 2X better if you can cheaply slow everything down, there's the Sensation Stone guy subdungeon (and possibly other ones, not sure), and there are maps where that thing is simply usefull throughout because of the monster roster.
I almost got pwned by Shifty Brickwork!