Round Corner Cantina definitely accommodates the hipster crowd and isn't ashamed to make it painfully obvious. Having said this, I really enjoy their drinks and their food and have been lucky enough to dodge the sour bartender and poor service I've been hearing about.
I have to stress that you really can't walk into the Round Corner Cantina expecting to be served promptly. I wouldn't walk in with an empty stomach. Instead, I'd bring some good company that you don't mind passing the time with. I'd order a few drinks and get lost in conversation and be pleasantly surprised when my comes. It's not a restaurant, it's a bar that serves food and it functions as one.
On nice, warm nights the outside seating fills up fast and they do not seat you. It is every man and woman for themselves but both times I've been, I managed to snag a table without any problem.
The food is fresh and tasty. Their tacos are pretty authentic with a bit of Portland thrown in. Every so often you'll get a pretentious piece of this or that but all in all, they're pretty close to the real thing. The drinks are mixed well and done right, using quality alcohol and a nice touch.
Go into Round Corner knowing that the service is hit or miss and that it might take a while to get a seat, it'll make you less surprised and offended when you're not treated like an eater so much as a bar goer, waving the five between your two fingers around in the hopes that you get noticed.