My first try at polymorph, as a life wizard I wore strong ice resistant clothing and thought I morph into storm as my companion was storm. I thought by morphing I could be of help to storm. Little to say, first time morph, and killed because I lost the Ice armor I had put on. This showed me Morphing is no good unless you face a weaker opponent than you. After I write this I will go remove all the morphing spells I have as you can not sell them and I see why, they get you killed. Stun three times by frost giant, then stun separately, yes as life I will stay life least I can stay alive. Morph into something, you have no control over armor or spells as the spells I got in morphing was not strong enough to do anything with. If the game wants me to play morphing they will have to do some strong improvements. My first experience getting killed, losing my ice resistant armor, no healing spells at all. I dare say I will do that again.
The only poly worth using is treant / jaguar, and then only in multiplayer PVE.
Gobbler is marginal at best, if you're low on health and have low starting health, gobbler inflates your health so that the amount you have left is based out of 5000 instead of your current max health. You also get a fairy-like healing spell.
Polymorphs are a bit UP (underpowered) in my opinion. Perhaps you would like to try Sun or Star. If you don't want to quit Polymorphs, Treant is always a good option...