- You have to be locked–in to their authentication service for it be effective. If you support TypeKey and still keep your site open to traditional comment systems, you are susceptible to comment spam.
- Embracing TypeKey exclusively (allowing comments from TypeKey users only) drives away casual visitors, like those from search engines. That may also include a friend who just discovered you have a website.
- Keyword: centralized. If some evil entity manages to hack into their service, could you imagine the possible amount of sensitive personal information involved? It could easily be the Patriot Act of Weblogging.
- Hundreds of sites pinging for authentication would surely produce a bottleneck, which could disable your entire commenting system. If for some other reason their service is unavailable, you break your visitor’s ability to comment.
These are my opinions, and we have yet to see how the service works in real–world conditions. Personally, I think site–wide comment registration would be more effective, combined with better administration tools and comment throttling. Still, the effort is much appreciated and the service worth trying, as we try to find the ultimate solution.