20 minutes later (the time it took me to get through the Terms of Service and the privacy information) I finally signed up. The process is really simple: You specify a username, password and email address. After that you can give some optional information about you: Firstname, lastname, ZIP-code (only for people who live in the USA) and your birthday. Then you get an email with an activation key for verifying your information and activating your account. As a last (more or less optional step) you can add 5 sites right away to your digest.
Adding sites is also easy. You don't have to search the RSS feed for yourself on the site but simply to specifify any URL of the website and then Kinja will search the site for the feed itself. It takes some seconds but those sites I've tried were added successfully to your socalled favorites. The problem with the favorites is, that you can't make categories for them. So all your websites are listed in one big category which is then used to create your personal "digest".
The digest looks like your classic news site with all the latest items listed in one column with some except of each entry. This might work if you just subscribe to a handfull of sites but I really doubt that it's usable if you have let's say more than 10 subscriptions. In my bloglines account I've currently more than 80 subscriptions. I'm not sure if I really want to import this list into Kinja ;-)
Importing a feedlist is supposed to be quite simple: Export your feedlist from your current RSS aggregator as OPML file and import it with 2 clicks in Kinja (http://kinja.com/import.knj). I've tried it with a small OPML file holding only 5 feeds in 2 folders. Importing succeeded and all feeds were added to this single one category on Kinja. The export also works more or less, but some of the exported feeds don't have a xmlUrl attribute.
The digest thing wouldn't be all that bad if I had found a way to mark entries as read. This way you have to remember yourself what entries you've already read which IMO makes the whole thing useless. There is also no way to make only specific favorites public. You only have the choice between making your whole list public or hide it as a whole.
Considering these things Kinja has still a long way to go until it can compete with services like Bloglines or Gregaire. I simply don't know if the current concept of the system is really usable :-( Sure, it is nice to read the digest of other people but without any useful structure or marking system I'm not sure what anyone would gain for creating his/her own digest.
Right before hitting the submit button I also did a small search on technorati and feedster about kinja and found a nice post by Jeffry Zeldman complaining about a fake-user probably set up by the developer team (probably for testing purpose or something).
I'm currently not sure if I will keep my account on kinja and for how long. I'm quite interested in how long they will be around and if they add some (useful) features, but I'll probably not use it for my daily weblog reading.