I own an 18 foot Alumacraft with a 70 Yammy. It has a tunnel and the pontoons on the rear. The positives are: Very cheap to maintain, although I do wash off after every trip which is not much different than a fiberglass boat. Just don't have to wax. As another poster has said, I have been stuck on oyster and sand reefs. Very easy to get off.
Just use a push pole. You will never get a fiberglass boat unstuck in some of the places I have been. I would have torn up a fiberglass boat. Light and easy to pull to boat ramp. The pontoons help run shallow and will help getting on plane faster.
Negative: Rough ride in a 3' chop and waves. Just have to learn what speed and slow down and then it does very well. Just cannot goes as fast through the waves as a fiberglass boat. With the tunnel, reverse does not work very well, very slow and tough to go against the wind in reverse. Slow but doable. The rear pontoons create a lot of turbulance. Therefore, a depth finder does not work very well. The depth finder works when sitting still, but when moving depth is all over the place, 50 to 300 feet and in only 3 feet of water.
I have owned 3 fiberglass boats until this one. I would certainly recommend an aluminum boat, if you just want to fish the bays. Nine years ago, I owned a 17' Skeeter bass boat and before moving to the coast I sold it. After moving to the coast, I bought this aluminum boat, thinking that after a couple of years I would purchase a larger fiberglass bay boat. But, I like my current aluminum boat for fishing the bays and will not purchase a fiberglass boat.