On the surface, event espresso looks amazing. It seems to have everything, and to be incredibly useful.
Let's say you're selling tickets to a conference. What's the most important thing for selling tickets? Well, to ensure that only people who have bought a ticket are registered for the conference.
Event Espresso doesn't let you do that.
For some bizarre reason, Event Espresso lets people rsvp for an event without paying for it. That has absolutely no value to anyone who requires payment for attendance. In fact, it has negative value, because the black hole of time wasted on communicating with attendees that, no, they don't actually have access to the event - BECAUSE THEY HAVEN'T PAID, BECAUSE YOUR TICKETING SYSTEM DIDN'T MAKE THEM PAY! - compounds the amount of time you have to waste figuring out who is going, who isn't going, and who still has to pay.
Foolishly overlooking this detail, and needing a good ticketing system for a project, I paid for Event Espresso's pro edition. Then I tried to address this - and other - problems. I went through a whole gauntlet of programmers whose job is, I guess, to customize the plugin for users. None of them, however, could fix the core problem with the plugin itself - that the plugin allows people who have NOT paid to think they have access to the event.
A giant waste of money and time.