I thought the first half of the series was rough, reminding me of some of the crappier Top Gear episodes, that is until the Christmas special, where I feel it really turned the tide and every episode since has been really enjoyable. Most of my complaints up to that point would be that the challenges seem rushed and unfinished, while the studio, err tent, segments are too obviously scripted, perhaps because they're playing to the audience more directly.
I don't like the driver, his dialogue is painful to listen to, it's always the same nonsensical whining. His whole shtick was funny in the first few episodes(much like celebrity brain crash), in that he's about as polar opposite of the stig concept you can get, but every word he says about a furrin car is interchangeable with the next one, I don't mind a hillbilly ranting about non-American cars but at least have some fucking substance to the rants.
Celebrity braincrash is more miss than hit, but I do prefer it to the insipid celebrity self promotion Top Gear interviews usually are(I almost always skipped those), but the last one was definitely one of the better ones lol. I'm hoping they phase that out in the future and extend conversation street focusing more on current auto news.