I needed it to allow people to register for classes at my training center. After doing a lot of research I thought this one would work best. Turns out that It did. I looked at DT Register as well. It also seemed pretty good, but the fact that you had to have jevents installed didn't fit my business/website model.
I also found that this extension had a better ADMIN demo than DT Register. Which fit my business better. Although I have to say, even this extension's demo was a little confusing compared to other extension demo's that I have seen. Maybe because it doesn't look like the default joomla template. Not sure.
As far as installing, it worked like a charm. It comes with the offline payment option and paypal extension.
However if you want to use AUTHORIZE.NET you have to purchase it separately for $19.00 from a separate company and it requires ioncube loader to install. Because I utilize godaddy hosting installing ioncube was a bit of a challenge, but once i figured it our the install worked perfect. Just make sure you follow the directions that come with the plugin.
Although I was a little disappointed that there wasn't a forum for questions and such, this extension's support was unmatched by any other extension that I have ever bought and I have been using Joomla for over 2 years. The response time is extremely short. One ticket was answered within 15 minutes of submitting it. Not to mention it was on a weekend.
My only negatives about this extension is that the Authorize.net plugin is a 3rd party plugin from osdcs.com. I ran into a few small snags and osdcs.com has still not responded to my ticket. It has been 2 days. I wish that Event Registration pro would produce their own Authorize.net plugin.
The other negative is that even though the manual is quite extensive on configuration, it is a little light on basic usage. Things like payment plugins. "make sure you have your paypal info filled in the plugin or it will not show up on the front end." & "Sorting events on the backend so that you do not get duplicate categories on the front end."
I have never tried it with community builder yet. that is next. I will let everyone know if any problems arise.
Overall this extension is a 9 out of 10, and is totally worth the money. I had been screwing around with some free registration systems before finding this one. None of them work right out of the box. So basically I wasted a lot of time and energy when i could have just bought this one and had it up and running in no time.
Anyway that is my 2 cents. Hope it is helpful.