Just got back. They only have 4 beers of their own on tap right now, but one was tremendous, two were quite good, and the other was solid. Based on the vision presented by the brewmaster during the tour and the beer itself, I wouldn't be surprised if this becomes Baltimore's best brewery in the not so distant future.
Note that I don't think that bar is as high as some other places as Baltimore has a decent amount of breweries, but none are elite IMO.
BTW, in terms of checking it out, they still haven't opened for normal business hours, but they just started having tours and tastings on weekends for $12. This weekend sold out in advance.
It's all about preference, but Union is my favorite. I'd call it elite by beer standards, though the brewery/bar itself isn't much. But picnic tables and cornhole outside, friends, great beer, that's all I need. I can't wait to see their new space.
If anyone hasn't tried their AM Gold yet, go down there and do that, and you'll want to take a growler home.