Probably Arnold would want a more coheisive and better continental army. Or just an army where he can go ala Bolivar/Napoleon like more high risk high reward strategy
Washington also would've wanted a more cohesive and better Continental Army, but he wasn't a wizard who could make it happen with a flick of a wand and neither was Arnold, that's just not how reality works.
He is called by the British the American Hannibal, aside from that, he was one of the most highly regarded and respected also revered and feared generals by the british in the Amercan side. Problem with the Quebec expedition, where he almost took Quebec city. Problems mainly stopped it from being a success instead a failure iotl
Again, citation on the British calling him the "American Hannibal" and fearing him? These are claims I have never heard and would want proof, he certainly never seemed to have displayed such tactical acumen to warrant such a claim outside of one victory which was not his alone.
Also, "problems stopped it being a success" is such a vapid and empty statement, what failures
aren't caused by problems?
EDIT: If the British feared and respected him so much, why didn't he get the pay raise and the promotion that were his conditions for turning traitor? His service in the British Army and treatment by his new comrades do not remotely indicate that they thought of Arnold as a crucial or even helpful ally.