For the most part, I liked this restaurant, and I'd probably be a regular if I lived in the area. As I don't live in the area, I'll mostly be focused on what can be improved.
1. No credit cards.
2. Awkward menu. It's $1.50 per perogi, but it's unclear how many you should order. Turns out 5 is large, 3-4 medium, 2-3 small.
3. They were out of bacon. They offer bacon or kielbasa for extra $2 with perogies. This seemed very lazy.
4. Some perogies are better than others, and I was underwhelmed by all the novelty perogies. The taco perogi, for example, was filled with taco meat. Nothing special. They should stick with what they do well.
5. I think the staff could be better trained. While we were eating, some dude--an employee with a goatee--came in from the back of the restaurant and started eating perogies in the kitchen in front of the other employees. We could see him while we ate! The restaurant has a clear hipster vibe that doesn't seem to be helpful. They will weird out some of the older crowd--the people who actually eat perogies.
Overall, I applaud the effort. It was a good experience, but it could be better.