It is certainly the best in my opinion. If you are into bittorrent downloading, you can get any one you want at Final Gear:
http://www.finalgear.com/shows/topgear/
The season 10 polar special is definitely worth watching...
I think the more recent seasons are better than the old ones, though the old one are more about cars and less of the quirky challenges.
You can also watch some of them streaming over the net at this site:
link
Enjoy!
p.s. Is season 12 over now, or are they on a holiday break?