I bought a cheaper one without wifi or Bluetooth... Just set the temp and let it run. I've used it frequently. Once the gas in my building was shut off for a few weeks and I used it to heat water for hot showers after getting a battery powered camping shower pump from Amazon. It turned out to be a surprisingly useful tool and I would replace it in a heartbeat.
I bought an inexpensive one online and it is pretty awesome. You can set your steaks for whatever you want, rare, medium-rare, whatever, and it's good to go after a couple hours. The cool thing is you can keep them "cooking" for a good hour or two after they are done, then when you're ready to eat, just throw them on a cast iron to sear the outside for a couple minutes and you have a perfectly cooked steak. I've used it for chicken with similar results.
I don’t use mine often, but I do enjoy it! It’s great for perfectly cooked steaks that you finish in a searing hot pan. I’ve used it for super tender and moist chicken breasts for chicken salad or pulled chicken. If you have a stand mixer with a paddle attachment you can drop the cooked chicken breasts in and it will shred them perfectly and quickly. I have a Joule that works with an app but would work without it, too.
I use the hell out of it during large gatherings and holidays. It’s great for throwing carrots, sweet potatoes, and meat into. You can throw them in really early then take stuff out as you’re ready to cook or serve it.
I got mine for a hyper-specific food allergy issue years ago. We still use it occasionally. It is tremendously powerful in how you can dial in a specific cook temp that allows for more tender meat than most other preparation methods, but it also involves a bit more setup and teardown than I like for most simple after-work style meals. I would recommend it if you have things in mind already and expect to get good use out of it.