There have been a few rough edges here and there, but it is actively being developed and moved forward all the time.
Due to the sheer volume of options you have, it can be a little daunting to configure at first, but I'd rather have those options and go through setting it up than not.
I wouldn't hesitate to recommend this to anyone that needs an event registration system on their site.
Also, the cost is minimal for what you get. A year of support and updates and almost instant responses to your trouble tickets. Awesome stuff.