Vista gets maligned but UAC is a good feature to have around, and Vista introduced it.
replyMy first thought was "But back then those prompts were constant, making them almost useless", though maybe that did actually help by making software vendors rely less on admin rights?
replyThat was the whole point.
replyUAC is not a security boundary. Malware can bypass it if it wants.
replyIt helps to actually enable having to type a password instead of clicking on Yes.
replyHowever yes, security is much more than an UAC dialog.