In short, 5th Gear is a "Five" re-hash of the old Top Gear format, and because it uses many of the same cast and crew, minus Jeremy Clarkson, it's a good one. It's like TG used to be a few years back, when the items were geared more towards information, although I will say that I have always found Tiff Needell entertaining when he track-tests a super-car.
Some have said that the show would benefit from Clarkson; personally I don't think so, partly because Five would probably have to be careful about not upsetting advertisers (unlike the BBC) and he has, shall we say, shown the potential for that!!
All in all, 5th Gear is a great show, and long may it continue.