A lot of thought on Tom's character, also by me.
At first we should all consider that Don trusted him.
His love towards the family is undoubtful, in my oppinion.A true and innocent love, which sometimes made him weak.
Not a wartime consigliere, as Michael rightly states.Not a Sicilian consigliere, as Santino rightly states.
But never a traitor."Michael I have always been loyal to you,why do you do this to me?"almost cries at the end of #2.
I think that he was the voice of reason and logic, but in a world where reason and logic isn't always the right thing to do.
Would be more helpful in #3, as a lawyer.
On the other hand,let's take under consideration the real consiglieri:their role was something like Tom:to advise their Don by reason.
Overall, I think Tom was a good guy.Not good to be a Don, weak perhaps, but Fredo was also weak...