As a beer geek (or as one friend constantly says, a beer sensei for reasons I have not yet figured out), having a place like Magnolia in town is a good thing. Not only do they have a fantastic selection of house made British and Belgian-style ales, but they also have some of the best Buffalo wings in the city.
However, it's not these things which makes them tops in my book, but these three things:
1) Handpumps - I think 5 of them in total, because real ale usually tastes better without added carbonation - and they're at the proper cellar temperature, not chilled to the level of the beer on CO2.
2) Guest taps - when they have the space, you can find beer from other local breweries or brewpubs on tap to compliment (or contrast) their own selection.
3) German ales - aside from Hefeweisen, there are only two indigeneous ales left in Germany: Klsch, from Cologne and Altbier from Dsseldorf. Not only are their interpretations dead-on (and I lived in Cologne for a while and practically lived in the brewhouses there), but they have sourced the correct glassware (stange and becher appropriately) which does add to the experience. Keeping these styles alive is aces in my book.
However, there are some downsides to Magnolia. Personally, when it comes to the music of Jerry Garcia, I'm grateful the band's dead... and Phish can go jump in a lake, which means that the music certainly isn't my taste.
Also, the design of the pub doesn't dedicate nearly enough space for the bar. I'd blow out a couple of booths and expand the bar seating so you can find a place to stand on a busy weekend. The lack of space at the bar when I am at a brewpub knocks a point off of the overall rating, but the beer is definitely worth 5 stars.