It's a start, but still too liberal. There are maximum age rules already enforced in other sectors (military), so I don't see why that is an issue.
House and Senate should be subject to exact same terms as the president.
Supreme court should also be something like 8 years maximum. We should not have situations where a justice is installed 3 or more presidents ago with no end in sight.
Break the two party system. I wouldn't even know how to go about that, but we need equal representation from other parties.
Finally, perhaps worst of all, is doing away with mixed legislation. What I mean is, if you are trying to pass X, then X should be only thing in that bill. It is unbelievable that politicians will also add A, B, and C to bill X, when none of them are related and almost always it is something that wouldn't stand on its own.
Americans should be furious that only two ways of thinking are allowed (Democrat / Republican) and that those entities have made it just shy of impossible for anyone else to succeed at top level. Does no one understand that democrat and republican parties are not established nor endorsed by our Constitution?