we flew jetstar twice. the first we travelled with a 18 month old toddler. it was terrible. the space in between seats were small and with him sitting on our laps, he could not stop wriggling out. shortly after the take off, he started to scream non stop. throughout the flight. totally inconsolable. on our way back to hk, it was much better. a kind soul gave up his seat next to us, so that he would not be disturbed. our tod ended up much happier with more space.
the 2nd experience was when he was 2 years old. had a seat to himself, happy camper.
the down part was transferring from airport to the plane, where we had to take the bus to get up the plane. it was crowded and the wait is long. and while alighting, i have no idea what the rush is, but we were pushed and elbowed all the time.
we never did take jetstar again. UA costs slightly more, but so much more organised and comfortable.