Fan cons:
1) Noiser than a troller
2) Slightly more work to steer, particularly in windy conditions
3) More gas
4) Have to watch out for fan height trees, branches, bridges
5) Sometimes, you go too fast
Pros:
1) Having a fan is awesome
2) No more troller tangled in weeds
3) No more troller hitting bottom and spooking fish
4) It's awesome
5) Go over logs, brush and other obstructions that would make a troller curl up and cry.
6) You can go faster
7) You don't get the water all mudded up like you do with troller
8) It's awesome
9) If you don't want to talk to somebody you can just say "Sorry, can't hear you. Fan."
10) It gets rid of bugs
11) Fish seem less scared of it than of the troller
12) If it has mechanical problems, you can likely fix it. It doesn't just quit and click at you like a broken troller, which probably needs another 'board' even though you just had the last one replaced last month and only had it on the water twice since then and how come it always takes two weeks to get the thing fixed? Heck they have it longer at the shop than we have it on the boat. And how come there's only one minnkota repair place within 40 miles? But I digress....
13) It doesn't drain batteries or need a converter. If you have gas, you have 100% power
14) It looks cool