Aikido is a serious martial art. Its techniques can only be executed if you truly intend to perform the technique. Therefore, "sparring" is of course a horrible way to prove that Aikido "works". First off, you and your opponent probably have some sort of gloves on, making wrist locks almost impossible. Second, if you don't want to actually hurt your opponent or don't have a nice mat for ukemi, most kokyunages are out. Basically what I'm saying is that if your resolve is not that of defeating your opponent, and simply "messing around", than Aikido will not work, period.
You mentioned the attacks are unrealistic. Ok, I'll give you that. However, how often is someone going to give you a nice centered zenkutsu dachi mune tsuki attack? Probably never, but karateka train against it and learn how to do it anyways. Why? So that by learning basic attacks, they will be able to defend against more advanced attacks, whether they realize it or not.
Does Aikido work? Watch someone like Ikeda-sensei, Saotome-sensei, Suenaka-sensei, O'sensei- and then tell me that it doesn't "work."
[Edited by Nick on December 1, 2000 at 10:47am]