Here is what I liked in each:
- Simple and elegant. Gets the job done.
- Has IM support.
- Good Facebook integration.
- The 140 character limit is more limiting than SMS.
- All twitters are public.
- No option to comment on twitters. The @ replies are confusing.
- Really cool interface. Ability to post text, photos, links, audio and video in one place.
- Import entries from other services like del.icio.us, flickr, twitter etc.
- Easy sharing of all my entries with people in my social-network.
- Ability to comment on entries.
- Entries can be either for self or public.
- Good archive view.
- No Facebook integration yet.
- The timestamp on imported entries is wrong (possibly because of timezone differences).
- Some of the entries are not imported – looks like a bug.
- Simple interface.
- Extensive privacy options for entries.
- Looks like there is Facebook integration (not tried this yet).
- There is no ability to import entries from other services.
All 3 services have API support.
I am still on the look out for a good microbloging service. I need some service that offers the simplicity of Twitter and the features of Tumblr. I will stick to Twitter until I see one service that helps me with all my requirements.