EDIT: It's been quite a while since the original report, and I'd like to update it with a lot more information.

It seems that when using the /tp command, the server and the client often have major disagreements about the rotation, momentum, and position of the player. When I filed the original report, it seemed to only result in the character's rotation being set to 0,0 and some occasionally choppy movement.

Now though, teleports seem to always result in choppy movement. Information about the teleport seems to be outdated, so to speak. It's most evident in the second attachment. When you have a series of teleports, any movement during the process is almost completely unpreserved. Sometimes even prior teleports are disregarded by the client leading to the character seemingly falling through the floor. The server always seems to get it right and the client eventually agrees, but until then, the process is an eyesore.

Viewing the two attachments, the first from 14w03b, the second from 1.8-pre1, you can see the major degradation of this feature over the seven months.