Survivors is excellent. One of the few early TNG-novels that still holds up today, imho (That one and Strike Zone are the only two, I think). It may help that it focuses on Tasha (who didn't had time to get fleshed out so much that there was a lot of contradictions later). I though Metamorphosis was ok. It works better as a continuation of the superior Survivors than a standalone novel. If I'm not mistaken, Metamorposis was the first TNG Giant Novel.