These are my initial impressions on using 1999.io. I'm using the web interface to publish.

These are mainly nitpicks about minor things that briefly confused me and for which I very quickly determined the answer. 

Signing In

When I first sign in to my.1999.io I am greeted with an empty text box that says "This is a good place to tell your story ..." Because my Twitter profile picture is to the left of the text box, and I'm asked to tell my story I'm confused about the purpose of the text box. It the text for a blog post or for a profile page?

Update: After submitting the text it's now clear this is my first post.

Adding an image

I added my first image to this post, but when I viewed the page there was obviously a problem as it wasn't centered and didn't seem to display properly. I remembered reading something about images, and a little digging turned up "Adding small images to stories."

Adding a smaller photo resolved the display problem and the image is now aligned-right in the text. I uploaded a 150 pixel wide image here, as recommended in the document linked above.

It might help if the language in the text box for the image URL said something like "paste a link to your 150 pixel wide or smaller image here ..."

Commenting

I saw that other users of 1999.io had comments on their posts. I was curious as to how I might turn on comments for my own blog. It turns out it's already available and accessed through the little downward triangle adjacent to the number of likes above the post. This is counter to everything I've experienced online about finding the comment link directly below a post.

It becomes more confusing when viewing a post that already has comments. Scattered throughout the comments are little reply links that only allow you to reply to a previous comment and not to the original post.

Overall experience

I like being able to just click on the text to edit. I like that creating a post is similar to adding an update to Facebook or Twitter and doesn't require going to a new page.

I'm curious, if I leave my browser open on my.1999.io will I see comments in real time? Based on what I've seen so far I believe that I would. That would be a very nice feature for live blogging.