The app has notifications but they can be easily disabled. Another reason to get the app is this:
They do this occasionally and it’s fun to get things for a dollar, so you might check it out. But be warned – you have to be very quick to get the dollar deal so be there right at turnover at Midnight Central Time.
As for how good the app is – it has issues sometimes but the devs fix it quickly once they are made aware of the problem. Pretty much like any other app, I guess. 
Oh, and if you ever try for a Bag of Crap, they appear slightly faster on the app than they do in a browser which can mean the difference between getting one and missing out.
Also, if you aren’t aware, the app runs on both iOS and Android.
(Please note: I don’t work for Woot, I just volunteer to help out here on the forums.)