If we're still talking about cook your own whatever, here's what I've tried, and my opinions of it.
Hot Pot. How it works:
You get a table, in the middle of the table is a big pot or two; the pots are often divided into reasonably water-tight sections. Each section of each pot has broth in it that you choose. For example, you can choose spicy beef broth and chicken broth - that's why you can get the pot divided so the broths don't mix, and why you can get multiple pots, depending on how many people are at the table. The broths have vegetables and whatever.
Next, they bring you a "menu" (since it's all-you-can-eat, it's basically a checklist) of various things, or you go to a buffet-style table of various things. Usually thinly sliced meats, vegetables, misc stuff like eggs, and more fun stuff like octopus or whatever. You select what you want, the bring it over, you drop it in the water until you decide it's done, you eat it. If you're still hungry, repeat and get new things until you're not. You generally get to try the entire menu, depending on how adventurous you are.
If you know how to make the broth at home, easy... it's called making soup. If you don't, it's not easy at all. Takes time and effort to make the broth base properly. And of course you would eat it as soup at home, and not a hot pot where you cook the stuff then fish it back out to eat.
Fondue. How it works:
They bring over melted cheese or chocolate, put it on a little pedestal with a flame to keep it hot and melted, and various things to dip into it. Dip. Eat. Repeat until you've finished your food. It's not really a you-cook-it deal, more like a you-dip-it deal. Easy to do at home, and much cheaper, but fun.
Korean BBQ with one of those hot plates in the middle. How it works:
You get a table, in the middle of the table is a propane burner (or natural gas or whatever), on top of that is a big seasoned cast iron grate. Generally, it's a lot like hot pot - menu, or buffet-style table - but the food is different. You usually get much thicker slabs of food (whereas hotpot slices to ~1mm, you're looking more at ~5-8mm probably) because you're cooking on a much hotter surface. The food is usually meat, seafood, vegetables; pre-seasoned and marinated. You get what you want, slap it on your thing, wait until you think it's done, and eat it. If you know how to make korean-style meat, it's trivial to do at home. If not, it's quite hard.
Cook your own steak type places. How it works:
You usually order off a menu, select your protein and your sides. They cook the sides, bring them over with the uncooked protein, and some sort of cooking apparatus (could be a super hot slab of rock, could be some sort of grill.) You cook the protein to your desired level of done-ness. Depending on the setup, you may find that instead of putting the food on, cooking it, taking it off, cutting and eating it, you instead cut, cook small pieces, and eat right off the cooking thing. It works pretty well. Of course, these tend to be pretty western-style dishes so if you know how to cook western-style food, it's much easier to do it at home. The key is to go to a butcher or fish-monger to get proper meat/fish instead of cheap grocery store cuts. To their defense, though, if you always find restaurant steak not cooked to your tastes, well, this gives you perfect control over doneness.
TLDR the more foreign (to you) the cooking style, the more it makes sense to go to one of these places. The better you can cook it yourself, the less sense it makes.
(This is also why I almost never order stuff like pasta dishes or burgers when I go out. I can make it myself, why pay 4x-10x + tip as much?)
I have been to all of these places and I am not exactly yearning to go back. Then again, I don't eat out terribly often either, I'm just reasonably adventurous.
Also, in case anyone is wondering, all-you-can-eat sushi (with a proper menu and fresh fish, these are hit or miss) is probably my favorite type of restaurant if they do it right. Again, not often, but once in a while... fuck yes.