In 18 yrs of having IBD I've gone through a few GI's, I'm on #5 currently and he's a keeper...what I've learned from my experiances are;
A good GI will be open-minded (especially since they don't know a whole lot themselves snubbing naturals or any other forms of therapy besides traditional meds really isn't their place).
One that is or has been involved with a research team regarding IBD (they tend to know a little more than the average GI that isn't or has never been involved in research aspects of IBD).
One that spends time with you (and doesn't snuff off your description of symptoms as being over exagerated or rushes you out the door).
One that takes phone calls (and returns messages).
One that isn't arrogant and tries to convince you or comes across like you'll never find another GI that knows this disease the way he/she does.
One that makes you feel that you are working together to fight your disesase, not one that makes you feel if you don't do everything they say you'll be sorry.
If anyone else has more to share from their experiances I think it would be a great help especially for the patients that are new to this dreaded disease.