Are you reffering to any specific one out of the series?
Well I've played the first SRT for the GB and SRT:OG 1&2 for the GBA. The first SRT was fairly solid in gameplay and everthing for its time. Featuring mecs from Gundam, Majinger Z, and Getter Robo. It was a mech fan's dream come true. The graphics were ok for its time, the battle BGM featured a remix of the show's themes and the story was good too.
As for OG1&2 I highly enjoyed both. For those not famaliar with the OG series it is ONLY composed of orignal units from the creators and do not star mechs or pilots from other famous anime series such as Gundam, Majinger Z, etc.
The OG series have a good solid storyline and the graphics are fairly good too. Especially in OG2 the units' movements during the battle are more fluid and realistic. In the first OG it was pretty much just the arms that moved. LOL. Most chars in the OG series have their own BG theme during battle and it really brings out the char's "feeling".
As for myself my personal fav. unit that'd be the Alteisen Riese, the pilot being Kyosuke Nanbu. I also like Ryusei Date in his R-1 which can combine with R-2 and R-3 to become the SRX and I love Latooni in her Fairlion. (^_^)