I've known about a dozen people who've done the Jetstar Cadetship in the past few years.
They were all generally positive about it, although a couple said they thought the Virgin Cadetship was better.
My understanding is that out of the last Jetstar course, nine started, one transferred to Virgin and seven went to London to do their A320 TR.
That's a pretty good pass rate, and while there is a lot of work to do in 18 months it's a relatively fast and reliable path to the airlines.
If I was a young person going thru today I'd do an integrated University-based course on HECS/HELP.