From my experience it's a pretty good blogging platform. I like it because it's easy to use, dose not require a database store but you can use one if you want to. Themes support, and more. It is also quite easy to write custom extensions and user controls for it. I myself have written about 6 different ones for various parts of the createdbyx.com site. All in all I've been pretty happy with it.

The code below is an example of how easy it is to implements a custom extension. This is a extension I wrote to inject creative commons info anywhere on a page just by typing [CC] when the page or blog post gets rendered the extension is run and replaces the [CC] string with the creative commons info. All you need to do is place the code file in the "App_Code\Extensions" and you are done!

  
#region Using

using System;
using System.Text;
using System.Text.RegularExpressions;
using System.Net;
using BlogEngine.Core;
using BlogEngine.Core.Web.Controls;

#endregion

[Extension("Replaces [CC] with a Creative Commons Attribution-Noncommercial-Share Alike 2.5 Canada License.", "1.0", "createdbyx.com")]
public class CreativeCommons
{
    public CreativeCommons()
    {
        Post.Serving += new EventHandler<ServingEventArgs>(Serving);
        Page.Serving += new EventHandler<ServingEventArgs>(Serving);
    }

    private void Serving(object sender, ServingEventArgs e)
    {

        while (e.Body.Contains("[CC]"))
        {
            int pos = e.Body.IndexOf("[CC]");
            if (pos != -1)
            {
                e.Body = e.Body.Remove(pos, 4);
                e.Body = e.Body.Insert(pos, GetHTML());
            }
        }

    }

    public string GetHTML()
    {
        return "<div align=\"center\">\r\n" +
                "<a rel=\"license\" target=\"_blank\" href=\"creativecommons.org/licenses/by-nc-sa/2.5/ca/\">" +
                "<img alt=\"Creative Commons License\" style=\"border-width:0\" src=\"i.creativecommons.org/l/by-nc-sa/2.5/ca/88x31.png\" />" +
                "</a>" +
                "<br />This work by " +
                "<a xmlns:cc=\"http://creativecommons.org/ns#\" href=\"http://www.createdbyx.com/\" property=\"cc:attributionName\" rel=\"cc:attributionURL\">Dean Lunz</a> is licensed under a " +
                "<a target=\"_blank\" rel=\"license\" href=\"creativecommons.org/licenses/by-nc-sa/2.5/ca/\">Creative Commons Attribution-Noncommercial-Share Alike 2.5 Canada License</a>." +
                " Permissions beyond the scope of this license may be available at " +
                "<a xmlns:cc=\"http://creativecommons.org/ns#\" href=\"http://contact.createdbyx.com/\" rel=\"cc:morePermissions\">http://contact.createdbyx.com/</a>." +
                "</div>";
    }
}