Jeep fiberglass body ??

Looking at a jeep with a fiberglass body , should this be a big negative ? Any comments ?

Not if it was installed correctly. Aside from grounding issues, it's really nothing to worry about. They're just as sturdy as a metal body for all things except hard core off roading, brushing up against rocks and trees usually does not end well.

The roll bar, if not tied into the frame, will be useless. There have been numerous fitmsnt issues with aftermarket parts, both interior and exterior. Plus side is it will never rust.

Not recommended if the intended usage contains any possibility for the Jeep to bang into anything else--ever! Bouncing off of tree branches, tree trunks, rocks, fences, livestock, other vehicles will just add a little character to a metal tub, but will make a mess of a fiberglass tub. For comparison, have you ever seen what a minor 'fender bender' does to a Corvette?