When you set the timer on most smartphones, the time end alert keeps sounding until the user acknowledges - the way it should be. With the this app, however, the timer’s audio alert lasts only a few seconds. If an airplane flies by, or if you turn on the blender or use a vacuum cleaner momentarily, the alert gets missed. I do realize that sous-vide cooking in general is more about temperature than time but there are applications when time is crucial, for instance, ChefSteps 75 degree eggs - which is what I just happen to use the this app mostly for. I’ve ruined many eggs by depending on this app’s timer and now use my iPhone’s timer instead.
On the other hand, suppose you stop the device manually after cooking because you don’t want to touch your phone with wet hands. The next time you turn it on and set a temperature, you must acknowledge that the water level is too low (from the previous session), turn it off from Joule , then restart from Joule . A big hassle.
Also, many of the time/temp recommendations provided by Joule are wrong. If you research the internet for time /temp recommendations, you’d be better off choosing the recommendations from other sources.