Is FeedPress compatible with Tumblr?

FeedPress works perfectly with Tumblr.

But you can't redirect your current feed to any feed service (be FeedPress, FeedBurner or any other service). Tumblr removed that feature in February 2014:
We no longer support syndication through Feedburner. Regular old RSS still works just fine, though. Sorry for any inconvenience this may cause.
This is undoubtedly terrible news for our own customers who rely on Tumblr. Unfortunately this means that any subscribers that subscribed to the original Tumblr feed will be no longer redirected to your FeedPress feed. At the moment, the less than ideal solution is to edit the HTML of your theme’s page and replace the Tumblr feed place holder with your FeedPress feed URL. We recommend adding a custom variable inside the HTML, and replace {RSS} with the custom variable. This is a more flexible solution than just replacing plain text.
Here’s an example of how we did that on our own Tumblr status page:

Note this line of code we added:
    <meta name="text:Feed URL" content="">
Copy this line and replace the content with your feed URL. Then you'll be able to use the variable `{text:Feed URL}` anywhere you used `{RSS}`.