Since Newsletter Studio is integrated to Umbraco you don't need to learn another system. It uses the same media items and the rich text editor is exactly the same as if you where working with Umbraco content.
Newsletter Studio can send your newsletters to members in your Umbraco site or to its built in mailing lists. If you need you can even extend it to get receivers from a web shop, CRM, web service or whatever you can think of.
If you want to have your newsletters listed on the site you could even add a tab to that document and send the newsletters directly from the content section. Since this is done using regular Umbraco templates you can include any dynamic content like macros, inline razor and much more.
After sending a campaign Newsletter Studio will start to track each receiver. In the analytics section you can see who open the e-mail and even who clicked a link or unsubscribe.
One of the main goals with Newsletter Studio is to make is as extensible as possible so that you can modify it to suite your needs. That's why we have Render Task to hook into the content rendering process and Subscriptions Providers that connects to external sources to fetch subscribers.
Newsletter Studio sends its e-mails using the SMTP-protocol which means that you can use your own server to send out newsletters or use a SMTP-relay service to handle the infrastructure.