Four months in, I've mostly stopped looking at those stats every day. Sometimes I can be super-careful and score a 2.5 or 3. Other times, I'm not thinking about it at all and get a 4 or 4.5. Here in Phoenix, almost every trip involves some high-speed freeway driving, so my acceleration numbers are always 1 or 2 stars, even if I stay in the right lane and put the cruise on just above the speed limit. I'll likely never see a 5.
And major peeve with the app. Say you're doing an across town trip where you really would want to see your stats. Say you drive from your home, across town 30 miles, then stop for a coffee. After your coffee, you continue another 3 miles to your final destination. You open the app to check your stats -- and they're only for that last, 3 mile leg, with no way to see previous trip stats. I've used the feedback option in the app to ask them to address this.