Wher there is levels or upgrades and points or currency in a game it allways make's it awesome to play and worthwhile. Looking at FF's it's very rewarding achieving levels and buying that extraordinary weapon, at the same time it's entertaining. As well GOW's or DMC's upgrading weapons is satisfying and overall makes the game look entirely different thus making pretty worthwhile playing and enjoy full. Therfore making it worth getting.
Getting the PS3 soon x] can't wait... hopefully the 160Gb Version :D
Never played it or seen how it works in real life :P
But I bet it will be awesome x]