I had the opportunity to work on a Mac with an SSD and was stunned by the speed. As the new Mac Mini (2.3 i5) had 2 HD bays, I decided to get an SSD (OWC 120 6G) and a bigger Harddrive (1TB Samsung M8). The Apple BTO prices are, well, ...pricey, but I wanted to speed up the Mini.
I'm not a repair pro and with this upgrade you have to be very patient and careful not to break anything. Everything in the Mac Mini is special, even the screws have different lenghts and sizes. It took me about an hour as an inexperienced user to get it done. The guide is very well made.
Take your time, don't force anything or you'll break something. It was well worth the time spent, I now have a super fast Mac Mini with enough storage. My advice on buying an SSD, get a 6G SSD (for a fast Boot Drive with all your apps) and a second conventional HD (It doesn't have to be a 7200, a 5400 will do).