Went out on one this year and was impressed.
For river running, it'll handle some pretty exciting water, class 3 or 4, I'm told, is no problem.
In addition, the thing is bullet proof as far as tipping goes.
Modifications I would make before fishing is extra storage straps and clips and a rotating 'bass-chair' seat. A MUST!! over the 'lawn chair'. Also, add a drag chain w/ pulley set up behind the boat (or for lakes an anchor).
Downfalls, paddling. Wouldn't want to be doing a float with the wind in your face.
Upside is sheer, unadulterated comfort.
Oh, if you're the front pax in a 1220, then prepare to get a bit wet.