Expect is great, however if you ever determine that using it is the best way to solve your problem, then you are probably approaching the problem the wrong way in the first place (the best way to proceed from that point may very well be to continue using expect though).

I used it a few years ago to create a test suite for some dedicated VoIP hardware (controlling the boxes over telnet). It worked great, but if I had had more time, that definitely would not have been my approach.