I can't speak for the PS3 versions, but I have to say that the PS2 games are pretty bad as games...but they are digestible for a TF fan.
The first movie game had some genuinely fun moments, but they got bogged down by a few very annoying levels that came out of nowhere. Maybe I just never found the right pattern to beat them, but I found the Ironhide vs. Blackout boss battle to be one of the most insidiously painful video game experiences I've ever had. Some of the Starscream levels were also irksome because of game controls...if you transformed in mid-air, you were totally vulnerable and defenseless until you landed (which meant it was unwise to transform at high altitudes). There were also some tedious racing modes which made the game feel like a hodge-podge of genres, although driving around Detroit suburbs as the level select hub is genuinely fun...especially if you decide to hold a demolition derby. Also positive, it was a ball to scale buildings as a giant robot, and there were some visceral thrills bashing bots. And playing as G1 Megatron is well worth it if you can find the game in a bargain bin (just unlock him with the cheat code--it's not worth playing the game through). There is a final level with Rampage style wanton destruction that Megs was just made for. The best part was perhaps how civil and military authorities would show up and attack you if you fought in public areas. It was a nice touch. I paid ten dollars for it on sale...I wouldn't have wanted to pay more.
As for RotF -- the PS2 version was a mindless slugfest...which might be fun if you are looking for an old school arcade brawler/shooter featuring Michael Bay robots. The one thing this game did better than it's predecessor was giving dialogue to the enemies. The game only lasts a couple of hours...so if you can pick it up cheap, it's a little bit of TF guilty pleasure. I bought it online for about four bucks. For the first hour or so, I actually thought this game was much better than the reviews said. For the last forty-five minutes or so, I was begging for it to be over. Oh, I almost forgot about the highly annoying puzzle mini-games that show up every so many minutes in the levels. You can skip them to fight another round of enemies...but they are just really weird. You have to arrange reflectors on a grid to redirect beams of light...but the whole thing plays out like some kind of home-brewed flash game and takes you completely out of the TF world. ("The enemies are about to detonate a bomb...call a time-out while we solve this sudoku!")
Both of these PS2 versions are bad when compared to other video games. However, as a TF fan, you'd be amused by them if you can get them cheap.