One of the main drawbacks of playing on GTA on PSP was the screen size. With the fat arse of the automobile that Toni was driving filling up the bottom-centre of the screen, the surrounding environment was squished around the edges. It was usable when the conditions on LCS were clear and sunny, but you'd be struggling to pick out oncoming traffic when it was dark and rainy. On the big screen it's a breeze.
The other big-machine improvement is that you now have the PS2 controller to cater for the many GTA actions, which makes a huge difference. While Rockstar did a decent job of mapping the commands to PSP, controlling the camera was always a problem. For instance you couldn't look back when reversing your car which made avoiding police cars when backing out of Pay 'n' Spray tricky, and you couldn't steer when doing drive-bys. Not huge problems, you might think, but when missions can be passed or failed on such small details, it all counts.
Above: It's going to take more than an Uzi to see off a four star wanted rating