I like that it allows me to see my open rates as well as click throughs which helps me see what emails are getting opened and clicked. It also gives you an idea of how many people have actually verified their email address with them. We use this service in our work so we can send out mass mailers without worrying about invalid or spammy emails being sent from our users' accounts. This has helped us greatly! There really isn't anything bad about using this software. You should definitely try it if you're looking into improving your email deliverability. They do charge for verification but they offer discounts for bulk orders. If you want to be sure that everyone who signs up for your newsletter gets validated correctly then this is the way to go!