I've tried several of these pop up plugins. Wowoptin has become my favorite. I always look at it from the users perspective and if it's hard to use from the beginning then I know the user's going to hate it. My first time test with wowoptin was pretty good. I got right in and started playing. It was intuitive and easy to find things. For sure, there are advanced features that will need to be explained to my clients, but someone can go right in and get things done. It made me want to come back and play more. I've used other products from wpxpo.com and they seem to have a great group of developers that make things work well. Over-all, I think it's worth the buy if you're looking for this kind of product or want to store it in your WP vault for later. I'll be implementing it into my plugin stack for my clients.