LC and I finished watching this last night. Going in, I had serious misgivings - partly because the first series exhausted the first book, partly because sequels are just never as good, and partly because the Pratchett/Gaiman pairing had a certain magic to it that Gaiman alone necessarily lacked.
So...
Yeah, it's good. It's not as good as the first series, but then I don't think anything really could have been. But Tennant and Sheen are now a well-practiced double act and they're both clearly familiar with their roles and also clearly having fun. And the series is just that - fun.
Ultimately, I do recommend it, and I'm finding myself looking forward to the third (and, I think, final) series. It might not work out, of course, but it has been left in a good place (from a storytelling point of view), and there's a lot more fun to be had.
Good stuff.