they are fine! I had one for 4 years
You have to feed it feeder fish or store bought shrimp. They hardly come out exept for feeding time. Beware of the size of fish you have though,some may go missing after he gets a little size on him. They grow partly on feeding. the more you feed the bigger he'll grow and faster.
Mine went from the size of an earthworm to 23" long and about 1'-1 1/2 in diameter.
thats in 4 years. The only thing i'd say is if you ever want him out, you'll have to tear your tank down. Think about it first. I'd personally keep him in a fish only tank, much easier. I had a good exp. with them but i had to take my tank down and i took him out while i had the chance.
Good Luck