I don't think so.
Lots of guys here Thinks Clannad is the saddest anime.
I never watch it but I'll try in the near futyre/

ummmm. it is really sad and the opening song is soooooo sad!!! :( it makes me think of my past ................... (sigh)

I think it is uniquely deep and delicate.
Personally I don't see it being sad, but rather emotional, in very tender sense. That's probably why I love it so much, it's refreshing in it's delicate handling of the life experiences of the characters.
Perhaps we can relate to one or more very deeply which makes it quite involving to watch and read.