Theyre fucking great and not big, so long as you already have a large stock pot.
There is no better way to cook chicken breast, or pork, or to slow cook things you don't want to pay attention to, or to make a shittier cut of beef taste better than it is. It can't do it all but it excels with lean protein.
It's also a fun way to make carrots still have texture but be cooked. Everything comes out very cheffy but meanwhile there is no possibility of failure.
It's almost cheating. It's so forgiving as to cook time, you put a chicken breast in, or a pork chop, forget about it, two hours later you take it out, dry it, cook it, sear it and it'll be the best you've eaten. I often make things hours in advance and just finish them at the very end. And if you forget to take it out, the window for perfection is very very long and it doesn't matter, since it can't bring the protein over a precise temperature.
I have one and it tastes great/ is super healthy.. But the real winning point is that I'm fixing lazy and this is perfect. Just rub some salt on, add a sprig of rosemary and dump it in for hours. If you're not out to impress a date you absolutely do not have to sear. Just slice and eat. The best part is, no oil splatter or smoke so no need to clean the floor after. You don't even need to clean the pan.