I use Google Reader for two main reasons. One is that once I subscribe to a feed, I get access to all messages, not just new ones. The second is that I can search old messages as well.
So if I understand Tumblrs inbox model correctly, that's exactly the kind of usage pattern that isn't supported.
The UI is very similar to a Twitter dashboard (if you are familiar with that). I don't think it's possible to search for old posts in either case, and the style of the site doesn't really lend itself to that kind of use (for better or worse).
I use Google Reader for two main reasons. One is that once I subscribe to a feed, I get access to all messages, not just new ones. The second is that I can search old messages as well.
So if I understand Tumblrs inbox model correctly, that's exactly the kind of usage pattern that isn't supported.