Complaining about games with weak final bosses (spoilers)

[MerrickG]

I know this isnt a news related thread, but I have seen many reviews to games that have been considered GREAT, but they one of the complaints mentioned is a weak final boss battle and I want to know what people didnt like about them or what would make them better because a lot of the time I just dont get the criticism. This thread has the potential to have major spoilers.

Examples are:
God of War 3 - Zeus battle. What was wrong with this battle? I thought it was epic and awesome.

Batman Arkham Asylum: Titan Joker. Again, why all the complaining?

Mass Effect 2- Human reaper. I thought it was challenging and very worthy of a final battle. Why all the hate?

Bioshock- why all the hate?

Assassins Creed 2 - not as much revered but a lot of people complained and said it was too easy.

Dead Space- I thought it was an excellent boss battle.

Infamous - I didnt like this battle because it ended up being WAY harder than the rest of the game, but as far as the battle itself (if played on hard) was challenging.

I want people to tell me what they didnt like and what would have made it better.