Well...the Jem dolls were sucky because you couldn't switch the heads around like the Barbies. In fact, I broke one of the Jem dolls trying to do that.
Another thing that annoyed me was that Jem was blonde in her Jerrica persona, and had pink two tone hair in her Jem-rock star persona. The doll came with a beret and you were supposed to tuck the pink hair under it so that would be Jerrica. I could never manage to do it.
But I still love Jem...just for the ridiculous eighties fashions the dolls wore and the tapes they came with.
Another toy that sucked was some of the She-ra gear I had. It came with a plastic crown, and bracers. The damn crown and bracers became bent and split very quickly.