MacGreggor's has lots of beers on tap, of varying quality, and as long as you stick to beer, you'll be more than fine. Particularly since their daily specials often feature some very fine beverages at outrageously low pitcher-prices.
Venturing into mixed drinks can be sketchy, as not all of their bartenders are particularly fantastic in that area. Sometimes the drinks are fine, sometimes they're underpoured.
The courtesy of the wait staff and bartenders is generally good. Sometimes not. Usually the waitresses are more pleasant than the bartenders.
The food is, as previously mentioned, "bar standard". Nachos, wings, burgers, etc. Not award-winning, but by no means bad.
Clintelle seems to largely be early-to-mid-twenties. College or young adult. LOTS of baseball caps and flannel shirts. You can't turn in any direction without being able to see at least one tv, so it's great for me during the NBA season, when I'm wanting to follow six games at once.
Overall, a nice place and a decent change of pace from my usual spots. Also, in addition to the metered parking mentioned in the review below, there's also a very large and conveniently free parking lot right behind the building.