I grew up there and have seen the town change slowly, for the better, throughout the years. The town still has it's quirks to put it lightly, but isn't bad overall. Billerica does have some traffic during commuter times, like route 3 north backing up northbound in the afternoon, or southbound in the morning. If you commute from Somerville/Cambridge area, you'll find you're largely always traveling easier as it's reversed. Traffic here is bad, but it really couldn't be worse and there are definitely areas you want to avoid if you can like the southeast expressway at any given afternoon, including weekends.