DQM is an amazing tool to create standard workflows which help us identify issues with our Business Objects, process them as per standards set by BOBs (BO =Business Object) & then fix those objects/data flows or remove from MasterDataBase(MDB).
This way we can keep track where each object came into MDBs life cycle so that if any issue arises at some point it gets addressed sooner rather than later thereby saving time  ;in case there was ever such thing like "Oops! We missed something". I don't really have anything specific against this product but more towards its pricing model compared other similar products available these days - maybe because i am not familiar enough woth all features yet? But still will try exploring further over internet before making my final decision one day :) Just do trial version first nd see how comfortable u get using dqm within few weeks only instead spending.