Most (but not all) of the IDW characters are really extensions of their original G1 personas, which I find really cool as it goes to show that the writers understand those characters and want to be faithful to the source material. I also love how Megatron and Galvatron are separate characters, which is also accurate to the G1 toy canon (and was reflected in some other G1 material like the Ladybird Books etc.). And where the characters are divorced from their G1 personas, they still manage to be interesting characters in their own right.