I'd say Gen Nav too, but only really because of the time pressure. Why on earth give you only 2 hours for what amounts to a 3 hour paper? What's the point?
Contrast this with the 30 mins you are given for the two Comms exams and hour for Human Performance. It took 3-4 minutes to do each Comm exam and 20 to do Human - and that's doing it twice just to be sure.
I found Met ok, but then I did do Met during the first year of my Geography Degree, so I might have had a head-start.
[PS: I'll stand corrected on the time given for the Gen Nav exam. Suffice to say that you don't get long enough by half!]