i'm glad my anova has both manual and bluetooth controls, because after the first couple of uses i simply default to manual for everything. personally i tihnk modern cellphones are remarkably clunky devices for anything other than reading books and gps. they aren't even very ergonomic as phones, they're annoying for web browsing compared to laptops, and they are definitely not satisfying to use as controls for physical devices.

And in two or three years, when that cloud service inevitably shuts down, you'll be stuck with a pot that doesn't heat water.

Mine cost a quarter of the app-based devices I've seen and the one difference is that I have to take a glance at a little table. I don't mind that.

And whether a device has controls doesn't matter with regards to hot water contact. It has to be properly sealed either way and capacitive buttons work fine for this (not worse than the low-quality buttons they'd use otherwise). The main feature you get with Bluetooth is another point of failure thanks to connection problems, at least that's my average experience with BT.

I recently got an Anova -- with touch controls, and it works great both with and without the app. The top is a big bigger to handle the screen and touch controls.

Making an immersion circulator app-only is likely a BOM-reducing measure, which is fine (given that active time is probably at most a few minutes like twice a day). And you can get smaller form factors too with app-only control (e.g. Ember Mug).

I guess I can see a push notification for a very slow cooking process, but most of the time if you use a smart device in a kitchen frequently, you're going to get things like uncooked chicken juices on it. Not ideal for a personal phone.