It's very sad to say, but the whole purpose of this character is just to annoy you and making some quests half impossible to complete.
What he does in the game is basically only following you all the time no matter where you are or what would happen by his actions, and he doesn't provide any aid or support in your battles either.
And unlike the other companions or NPCs, even if there are visible traps, he never avoids those and runs straight to you although he is supposed to be a very smart wizard. It would have been more understandable if he were some kind of baby squirrel knight who is a bit clumsy or something (He could have been more adorable and forgivable, I guess), but he is a very old squirrel knight / wizard who believes he is much smarter than humans or the others.
Then as you can imagine, it doesn't really matter how careful you are, he triggers all of the traps around you and this could actually kill the whole of your party by making the field blazing fire.
So although his personality might be fine as it is (I actually don't even dislike him. He has a nice personality), when it's connected with this stupidity, his arrogant attitude becomes quite annoying to be honest.
And there are some puzzles in the game which would be almost impossible to solve because of this behaviour since he stands on random pressure plates all the time while we need to stand on only certain ones. I don't really understand why there is no "Unchain" function for him while we can do it with the other companions.
And also, although he sometimes gives you recipes of some skill books, there are no unique skills or anything, so the ones he gives you are all available without him.
Lastly, while he has lots of dialogues, there is no actual story / quest / event at all.
Therefore, he is practically just a very very long flavour text who can ruin your game experiences.
It could have been better if he had some real stories connected to the main ones and he could actually fight along with us. Probably in the last act or so, so the adventure with him would be much more rewarding.
I imagine how exciting it could have been if he could really find what he was looking for in the end and uses his unique powerful spell toward our enemies. It would have been really cool, but the truth is, there is nothing.
Very disappointing.