GT4 got boring because I had to constantly go out in the stupidly fast LM cars, or cripple the ones I liked with standard road tyres.
I agree with the post aboive that the game needs HP limits to offer some incentive to complete a series...
The 2CV races... I sat through the stupidly slow uncomptetitive races and expected maybe some sort of fun concept Citreon... Nope, here's a pink 2CV, now carry on being bored and B speccing everything...
Saying this however, I have just bought a PSP to play GT4 mobile and despite my anti-sony ways, GT5 could persuade me to go PS3... Also the whole PSP-PS3 linkup could be good.
I personally think the Revolutions controller looks like an annoying gimmick and I'll be avoiding it like the plague. 360 seems decent enough to me, and at least it's available now... (sort of)