Hm... well, I guess they poop. That's the only con I can think of... OH! You need to feed them! lol
They have pretty good disposition. All my adults are very tame and have never struck or bitten (except at food, or once my hand which unfortunately smelled like a mouse), and I rarely handle mine. My littlest female is a little on the wiry side, but when I handle her more often she chills. My male is just a doll... I take him out and he just wraps around my neck for a few hours

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While they aren't as tame as a burm or a boa, they are far from crazy. They just tend to be more active. My big female will get impatient with me if I have her out for a long time, and will warm me with little loud-breaths.
Even my babies are tame. They are a little zippy, and slither around my hands, but never try to "run" away or bite me. I was struck at once by one of the babies when attempting to untanbgle him from some heat-pad wires. However, even then it was a warning snap, and he could have hit me but didn't.
So, their tempermants are better than that of any JCP i've ever met, but coastals do tend to be calmer. But they come with a bigger size.
Also, IJs make great display snakes! Mine are always out and about, and rarely hide.
Zoe