Is there a reward for beating the Truth puzzles other than the achievement?

nope, not that I could tell

I'm bummed that some stuff like 100% Rome or getting all your assassins level 10 don't have achievements.

Spoilers pertaining to the Truth puzzles below:
 
 
 
 
 
Completing the truth puzzles actually felt insulting to me.  It was like the Devs had built up a compelling and interesting story throughout the three games, and then decided traded all the good will and clout they've built up and bludgeoned us with a conspiracy theory we've already heard on CNN.  I wasn't expecting a big reward per se but what I got felt like a booby prize.  Gone was the interesting tidbits that made up "The Truth" in AC2, and in its place I watched the game story engage in partisan politics?
 
Sarah Palin, Dick Cheney along with Supreme Court Justices Thomas, Scalia, Roberts, Alito, and Kennedy (basically all the conservative and moderate justices) are all members of the secret Templar society?  Sounds like they need to add "political views" to that disclaimer they put up every time you turn on the game about being a multicultural dev team with many religious beliefs...
 
To be honest I'm not really annoyed they went this route because it is partisan, I would be almost as annoyed if it swung the other way.  Picking a side like they did really diminished the Templar in my eyes, historically they have been successful because they control ALL the sides, why they would suddenly pick a specific side the second G.W. Bush was elected makes no sense at all in the context of the story they have written and it really comes across as a cheap political swipe rather than an interesting twist in the story.

Teran - I'm a moderate democrat, and I agree with you.  It felt extremely ham-fisted.  Especially the focus on the Citizens United decision as pro-Templar.  Abstergo Industries would hardly be limited by American campaign finance laws!  Very knee-jerk, and very much a non-American's view of American politics.
 
There was also a reference to people who opposed healthcare reform being wrong in one of the entries in the database.  Weird.