Spoiler Alert!I hate it when games do this. They make the final boss so easy that I would be very surprised if anyone actually died against him.
I think Super Mario 64 had a great final battle, because it actually took some skill to perform the final Bowser throw onto the spike-bombs off the level.
I loved SMG, but when finishing the final boss with 137 lives left, you can't help but feel a bit dissapointed.
(Before you go "137 lives? You lie!" I did it all in one go, so my lives never went back to 5.)