Compared to classics such as Thunderbirds, Stingray and Captain Scarlet, Terrahawks paled in comparison. However, to be fair, let's judge it on it's own merits. Perhaps comparing an 80's puppet show to a 60's puppet show isn't ethical.
Terrahawks featured a military unit called Terrahawks (led by Dr. Tiger Ninestein) against an evil alien called Zelda (easily the ugliest character in any TV show) and her even uglier son Yung-Star. Zelda is one of these aliens who won't settle down and get a hobby, preferring to conquer the Earth instead (I wonder what these aliens do for fun after they've conquered a whole planet). Anyway, Ninestein and his Terrahawks Unit (which included characters such as ace pilot Hawkeye) battled the evil forces of Zelda each week. Joining the Terrahawks were two annoying but loveable robots Sgt. Major Zero and Space Sgt. 101 who were usually getting on Ninestein's nerves.
The show does seem rather dated now. A new process was used in the TV show-supermacromation where the puppets didn't have strings(unlike Supermarionation which used strings in the 60's shows and paradoxically, looked better). I don't know if I'd enjoy it if I watched it now. And whilst it was largely enjoyable, it was lacking that certain something that seperates a good TV show from a really great TV show.
But, all in all, kids will love it and it did have it's moments. Enjoy!
