There is a followup post here that goes into quite a bit more detail. If you are interested in this topic I recommend you read both, as well as take the time to go through the comments. There is some excellent back and forth on the benefits and downsides of each.

As someone who manages several blogs, some on TypePad and some on WordPress, I find myself in a rather unique position to comment on both. I won’t lie- I am clearly biased towards the latter, and though my opinion might be colored by that bias I’ve tried to figure out why I feel the way I do. I’ve outlined a few points below on areas where I feel that WordPress is clearly superior to TypePad.

Feature Implementation

If you look at a strict feature list of each system, it seems like while there are a few tradeoffs, the two systems are effectively equivalent. This is not entirely the case- hosting on TypePad gives you a series of admin forms that… well, don’t really feel like admin forms. Figuring out where all the customization settings are is almost as much effort as the customization itself, and no real thought has been put into UX or context. To contrast, the new WordPress UI has clearly received quite a bit of love from people who aren’t developers: The design is clean, management and updating is easy, the help files are easily found and concise, and if a particular feature is implemented it is done so in a way that covers 95% of your use cases. In other words, it’s a much cleaner experience.

URLs

This is perhaps my biggest issue with TypePad, and is best illustrated via the following samples. Please place close attention on the URL’s themselves.

Sample in Typepad

• Root URL: http://www.cuteoverload.com/
• Article URL: http://mfrost.typepad.com/cute_overload/2008/06/rule-of-cutenes.html

Sample in WordPress

• Root URL: http://www.flashenabledblog.com/
• Article URL: http://www.flashenabledblog.com/2008/06/12/tutorial-creating-a-downloader-for-youtube-with-flexair/

For Search Engine Optimization this is a deal breaker – on WordPress, the Search Engine Spiders see all of your articles under your domain. On TypePad, they see a single page linking off to a bunch of pages on typepad.com. In other words, TypePad gets SEO credit for your content. Note that this is a double-edged sword: by having your content on TypePad you get a small automatic SEO boost simply because you’re affiliated with them, yet the tradeoff is that you’re far more likely to get lost in the noise.

User Registration

On WordPress, anyone can register and comment, and they get a handy dashboard once they do. On TypePad this is not the case- even if you’re logged in as a user on TypePad, you will still be prompted to sign in to TypeKey to be able to retain your identity across blogs and comments. On top of that, your registrants will be bombarded with requests to start their own blog, and while my marketing side can appreciate the cross-sell opportunity, the user in me finds it incredibly obnoxious.

Extensibility

This will probably not come into play unless you’re interested in hosting your own blog and/or have a developer mindset (like myself), but WordPress is simply easier to customize. Even if the metric fuckton of extensions and plugins doesn’t suit you (the kitten-a-day plugin is my personal favorite), the fact that the codebase is fully open sourced makes it easy for third party developers to generate their own. In contrast, TypePad itself is really not customizable at all, and Six Apart’s self-hosted solution Movable Type will cost you money. Admittedly, they do have a few plugins that are superior (Piknik for one), but given the ecosystem I expect an enterprising developer will meet and exceed them soon enough.

Upgrading

Sooner or later, you’re going to want to upgrade and leave your hosted solution for your own server. If you’re on Typepad, you will probably be looking at a variety of different solutions, including Movable Type (published by the same people who publish TypePad). If you’re on WordPress, you’ll probably be looking at… WordPress. Movable Type has licensing fees, and while they’ve made strides towards open-sourcing the core of their system they still retain IP control over the real juicy bits. In contrast, WordPress is entirely free, and given that at this level the two systems are functionally equivalent, the upgrade path from WordPress.com to your own installation is much easier, cheaper, and builds on your existing system knowledge so you don’t have to learn everything over again (On top of the UX point I made above).

Furthermore, WordPress has an ace up its sleeve: WordPress Mu. This is the upgrade after the upgrade, where you become the host of other people’s blogs. The install is practically the same, the only difference is that now you’re in charge of the "WordPress.com" equivalent. While competing with them directly might not be the best option, this is an excellent system if you are interested in opening your own office to blogging. Anyone and everyone can create their own blog and retain their own author identity, while at the same time remaining associated with your company. OPENing up your office culture can be a boon in many different ways.