Our previous breathalyzer took a full minute to be ready to go - sometimes longer. This one is ready to go in less than 15 seconds. It seems to be pretty accurate as long as you heed the instructions and WAIT 10 - 15 minutes after eating or drinking ANYTHING before blowing. My husband blew a .20 about 10 minutes after finishing his last drink one night, then drank water a bit later and blew a .07. (He was still a .09 when he blew about half an hour later after not having anything else to eat or drink.) This is worth the money if you want to make sure you're safe before driving