I am moving to Lyons in the New Year!
It depends on what you're looking for. Lyons has a population of about 1600 people. There is one bus service that runs to Boulder Mon-Fri during rush hours only, but RTD of Denver is considering expanding that service since its usage went up nearly 25% this past year. There is a small public library, some nice coffeeshops and restaurants, a pretty good restaurant/bar/live music venue (Oskar Blues), a few antique/junk shops, a Montessori and high school, it's very close to the mountains and other mountain towns such as Estes Park and many trails, as well as having (I think) two rivers running thro the town. It does NOT have a large supermarket but a small regular one and an organic one. Shops are not open on Sundays in Lyons!
If you check out the town's website (
http://www.lyons-colorado.com/) and look at the Events calendar, you'll see there are several festivals there during the year. The two biggest are the Bluegrass Festival in July and the Folk Festival in August. These bring a LOT of people into town and liven things up considerably. This is a good website to get more info about the town and the Town Clerk there is very responsive to emailed questions.
Basically you're looking at a small town with not much infrastructure, altho reading the town's plan for the future they are looking to develop the "downtown" area more. It can be very quiet at the weekends but there's usually something going on at night. People I know who live there already tell me that anyone who moves to Lyons ends up loving it. Lyons people are not particularly outgoing but once they get going they're pretty fun and love to talk about how great Lyons is. I'm told it has the cleanest air in the county, temps in the Winter are 10º lower than elsewhere and 10º higher than in the Summer - probably because of the shelter received from the surrounding cliffs.
It's about 20-25 minutes' drive due north from Boulder and whilst its property is highly desirable as a "Mountain Town" and therefore a little more expensive, it's not as bad as Boulder. It'd probably be a good idea for you to come to Lyons and have a look around during the day, weekend and the evenings to get a proper picture.