Apparently 4 stars on Yelp in the middle of Hell's Kitchen. If this is 4 stars then it explains Ippudo's popularity, there's no competition.
Chicken based stock is pretty good, sweeter than the pork one. Noodles (2 different types) are apparently house made and were ok but not spectacular. Don't bother with the steamed bun.
Overall though it doesn't feel like ramen. It feels like an early ancestor from China in the days before ramen became distinctively Japanese.