I bought this item because I knew there were a couple of watches changing hands as presents over Christmas and I thought it would be nice to be able to adjust them there and then. The unit did come with instructions, but these were basic and of no real use. So, how did I get on?
At the first attempt I bent the pin remover - so lesson one is probe very gently to get the pin out. When you have it lined up correctly I found it slips out very easily so if you are meeting resistance you have not got it lined up correctly - keep trying until you do and do not try to force it out. I was lucky enough to be able to straighten out the pin remover without breaking it. Incidentally the instructions refer to a replacement for this part so if this happens to you and the pin remover bit breaks, its worth getting on to the seller and enquiring.
I successfully adjusted two watches but I would not describe it as an easy process and each took 10-15 minutes of fiddling around to get the watch lined up correctly in the tool. There is a strange mechanism which moves the bed which the watch sits on backwards and forwards. I am not sure of the use for this. If you were able to move this bed up and down to line up the pin it would actually be useful.
On point which sounds rather obvious, but is not so clear in practice, is make sure you are pushing the pin from the right end. The end to be pushed is usually indented a little into the band whilst the other end stands out more proud to the band and often has a cross thread on it.
You need something to put the pin back in. I think jewellers use a tiny hammer. Do not go and get the hammer from the toolbox though! I found hammering down gently with the wooden handle of a kitchen knife worked very well with no danger of damaging the watch or alternatively just pressing down with something wooden or plastic should do the trick.
So to summarise, yes it does work if used carefully. However, its a fiddly process so do not bother unless you have the patience to mess around with it. I do feel that a bit more thought could have produced a much more user friendly tool.