After Lilly and Marshall get back together they decide to get married right away to avoid the awkwardness of dealing with Marshall's family. This was a great story. I like how Lilly proposed and Marshall wanted it to be special. A great callback to the pilot after Marshall proposed. It's things like this why I like this so much. If you have seen all the episodes at this point, you appreciate it more. While I am not a fan of quick marriages, especially for great couples like Marshall and Lilly, I am glad there was a sense of realism to getting the wedding together. Most shows the wedding just happens with little conflict or happens because of beer. It was funny how Ted was turned on by Robin's shirt. The scene with the first Registrar was very funny. She delivered with the perfect touch of empathy and yet still knowing how to do her job.
Another good thing was Barney. You are left wondering on why he is doing what he is doing. (many episodes you do, but this one especially) While the show did explain what Barney is doing, I don't feel like the whole story is explained. I really like this. Another callback to season one when Marshall figuring out the game.
It was real nice ending and good turnaround for Robin. My only complaint was it gives people hope who want Robin as the future mother. Overall this was a good episode that left some mystery up in the air and sets up nicely for the next episode which also has some mystery.