I bought a new PS3 Slim after my old PS3 (one of the earliest models) broke. As far as I was aware at the time of purchasing it was just a smaller version of my old one with greater storage space. However, I was pleasantly surprised.
It works just as well as the older version and start up is a lot quicker from my experience however, cooling unit seems to be louder which can get annoying but is mostly unnoticed. Graphics have seen no improvement but that was not expected. For a smaller unit I was expecting perhaps longer loading times and longer start up but that is completely not the case, the console works much better than the older one. In my opinion it is quite expensive but as long as it stays working as long as my last one I will be happy as it is one of the best if not the best console on the market.
I would definitely advise people to get this if they need a console that is not only good looking but also works incredibly well. For those whose old one is still working, unless you are struggling for storage, I suggest holding out for a new upgraded console as this one, whilst working well, is not a real upgrade as far as gaming is concerned.