I'll add my impression so far after about 6 weeks. Fills have been ok although I would definitely give an edge to IB. My biggest annoyance with Tradier is that they do not allow any modifications to a partially filled order. They also do not allow you to change quantity on a spread order once you've submitted - price changes are allowed but not qty changes.
I spoke to them about the order modification limitations and they said it's a common complaint but they do intend to support at some point in the future.
