Considering most jewelers charge $10-$20 to adjust a watch, this is a great buy.  Yes, it is not the highest quality piece of equipment out there but it costs around $3.  I have used this to resize my new watch and I am happy with the results.  It pays for itself in one use!

Note:  I saw a few reviews saying that the plastic handle "snapped".  The handle will come out if you unscrew it all the way (which is actually beneficial because I used the handle by itself to push in spring bars)... you can just screw it back on.

Update:  It is now in the trash after 2 or 3 uses... the plastic handle did in fact fall apart... but for $3, you can't really complain.  Sure beats going to the jeweler.  I plan to buy another set, but will probably spend a little more on the "mallet" kind.