My mother is a blogger. She is also using dial up. I have not ever seen nor used a dial up connection that I trusted. Dial-up can get the job done, if you are not in a hurry.
But the thing that irritates me, and Mom, the most is when lose your connection on a nice, long, post. (And you know that you will never be able to recreate it!)
That is where bloggar comes in. You can compose all of your posts off line and post when you connect. Bloggar supports most of the major blogging software. It has the basic features for formatting and spell checking that are so necessary. It also has features for uploading images to your server, whether you are using your own or an image hosting service to store your photos for your blog.
This may not be necessary if you have broadband, but may also be of benefit to those that that have a high speed connection. The Interface is WYSIWYG (what you see is what you get) and you can even further define that by actually calling to the style sheet of your blog to display your post preview.
One feature that I like is that you do not have to open another browser window to publish to your blog. You can open up Bloggar right there and be able to see what inspired you as you write your post.
I do not have enough experience with this to make a statement on whether the code it generates is valid or not, but unless you make several changes in the formatting, I do not see where it would be a problem.