From your pictures, it looks like you have the aluminum roof. That's good. It shouldn't sag. (If you had the fiberglass roof, it would probably be bowing and gapping. I replaced mine under "warranty" but still had to pay $600 for shipping.)
You also have the tubular brace on the ceiling that was supposed to be installed with the air conditioner. That's good also.
I agree with an earlier poster that there is a small drain tube that easily get plugged and the water backs up inside or drips inside. Can't tell you exactly where it is though...
If you think the roof looks uneven, your cables may need to be adjusted to level the roof.