More and more riders are buying "on-line" as choices and availability are much greater than what some local bike shops offer. However, many new riders are not comfortable with ordering out for a bike...the right frame size could be a problem if not researched. To assemble, you just need a few basic tools and 15 minutes of time to put the stem/handlebar in headset, pedals on, seat/post in place, reflectors, check skewers for tightness...thats about it. I have bought 3 boxed bikes over the years and have never had to adjust derailers, shifters, or brakes. If you are not the fix-it type, a local bike shop can do it in the $25. range.
Ride safe.