The initial features included in the first beta version can be found in @howo's post here
https://steemit.com/utopian-io/@howo/introducing-steempress-beta-a-wordpress-plugin-for-steem
The new added features are listed above.

SteemPress, at the moment, is mostly useful for WordPress users who want a quick and convenient way to share their new posts also on steemit. We will want to build a stronger and stronger connection over time and add more features that synergise with STEEM as we progress. But currently, it only converts the text appropriately for markdown and posts the content you add to your wordpress blog to the steem blockchain.