How I Use It
I use this website when I'm running student debates so that the audience feels like they're a part of the action. While the debate is going on, there are questions being posed and answered by other students which really allows them to discuss the material. What's more, I can jump in and answer any simple questions quickly (e.g. "How old did he say that law was?").
Another nice feature is the ability for students to be insta-polled about various topics; I often will throw up a quick poll to see who the audience thinks is making a stronger argument or whether or not they understood something complicated that was just said. It's not only nice for me to get instant feedback--it's nice for the student participants in the debate so they can can adjust what they're saying in terms of clarity and/or strength of argument.
The only potential negative is that students are on their honor to enter their correct names and if you are not vigilant with checking to make sure every student is participating under their true name, they could hit you with some anonymous and uncivil comments. A feature for the moderator to be able to boot students from the event would be nice so that this could be quickly weeded out rather than having to shout "wait a minute, who is weedman420?" to the class and try to narrow it down at that point. So long as you're vigilant and take "virtual roll", it should be alright.
This is a great product and the price (free) is right. The students like it, it has a smooth interface, and the overall effect is strong and intuitive.