O'Briens is a top notch neighborhood dive bar. Don't expect anything too classy, but the food is good and after a few visits, the bartenders will know your drinks, and probably your names. It's a busy after-work stop, so it can get crowded on certain days of the week. Pretty great place to watch a game, play some pool or shuffleboard, and hang out with friends.
Smoking section is awesome. I don't smoke, but this smoking section keeps the smell of smoke out of the non-smoking side without segregating the smokers to some nether world away from the rest of us. Perfect compromise for a bar environment.