The plus side? 21st Street is a local shop and takes pride in their drinks. The espresso is good and they have cortados on the menu (my drink of choice!).
The downside? The space is unwelcoming and small; lacking that warm vibe that you tend to find at most coffee shops. I can't imagine ever wanting to sit and work in such a space, despite the free wi-fi. The staff also has an air of arrogance that can be very off-putting. It's as if their commendable aim to be coffee/tea purists demands that you be a purist drinker, as well. Also, if you prefer your latte with skim milk, don't expect it at 21st Street. You're limited to whole or 2%. It's one of those little things that might send some customers elsewhere. I know we've resorted to passing up 21st Street when we were in a latte mood for this very reason.
It's also a bit expensive. For example, we usually get two cortados for about $5.50 at other places. Expect to pay nearly $2 more for them at this downtown location. I love supporting smaller shops, but 21st Street hasn't won me over yet. Hopefully that changes.