What do Teutons Need?

I will be first to say im not that great at the game and am still at the level where civ doesnt matter nearly as much as being better at the basics. But i tend to see people saying Teutons are near the bottom of the barrel as a civ pick, which has me curious as to why they are considered bad. I always thought their farm bonus made up for some tech tree deficiencies (outside of a super situational unique unit). So what do you think they are too weak at and what needs to be done for them to be a more balanced civ?