My company had this for a while and it has worked great and did everything you'd expect for email and signup software. We can have people opt in quickly and easily with a series of premade forms or customize a form. We actually just used the basic form with contact fields but you can also add text and colors to customize it and add to your website. Emails can be customized or started with templates so you know contacts are receiving newsletters that are properly formatted.
Some of the customization options limited so when we really need to have something look a certain way, the text or spacing might be slightly off and is difficult to fix without coding knowledge. Customer service might not know how to format certain things either.
It's a popular and reliable software and not very expensive so it's a good starting point. You can use many tools to customize the look of forms and emails. If you want something that can be tailored very precisely though, then this might not be the best option.
Automating contact optins helps save us time and keep us within emailing guidelines. We can get emails out in a timely fashion are create lists for certain contacts and with specific topics so they're more likely to convert. We generally convert more when we send emails.