Its very good IMO. It appears to be a port of a not-quite final release of MKT for PSX so it is a bit buggier and floatier then the last version of MKT for PSX. But, it is very good, and it installs to your HD and only uses the CD for music so there is no loading time.
There are at least two, the first and the last, but there might have been one or two in the middle too. I played the orange disc, the grey disc and the greatest hits version and didn't really see a difference but it might have been subtle.