Good and Ugly of Ajax

I found "Thank God Java EE Is Not Like Ajax" to be an interesting subject, esp. the quote form Coach Wei:

Which aspect of Ajax [do] we really want Java EE to be like? The difficulty in developing Ajax code? The difficulty in maintaining Ajax code? The extreme fragile nature of Ajax code? The extremely fragmented nature of Ajax support from different browsers?

Ajax is hot but it's also a pain to deal with [as far as I can tell: I haven't done any real programming but I get enough hearsay to feel the pain].