For me the scent is very long lasting. You can choose the setting on how often you want it to spray. Mine only sprays every hour or so and you can smell it through out the whole house all day. I never lose the smell.
Scent is pretty consistent, but we've had ours for a little over a year and it just broke. It started spraying every 30 seconds (not even one of the settings). When it did work, the batteries lasted at least a couple months I think