I fly between Melbourne and Sydney often these days, at least once a month.
After several delays and cancellations, I decided that no matter how much more it costs, I will never ever book a Jetstar flight. You think it's more affordable, but in reality - you incur the costs of their delays and cancellations. There's also the hidden cost of using your annual leave from work, due to these delays and cancellations.
It always ends up being much more expensive.
I recently had a flight cancelled, after reaching the airport and waiting at the gate, due to "weather conditions". Apparently there's a clause in Jetstar's terms of service, which exempts them from reimbursing you from any costs incurred by said delays, such as taxi/Uber rides, hotels etc. Despite the supposed "weather" issue, the next flight after hours departed successfully, and other airlines were also flying as usually. It's not like there are hurricanes in Sydney in February.
After more than an hour of delay, all passengers were told to leave the gate and go to the service counter. The queue for the service counter took over an hour too. When we got to the service counter, the staff member told us she cannot help and rebook us on the next flight, or make any booking changes at all - but guided us to talk to their customer service.
There's no phone number to call, you can only communicate with their customer service via a chat webpage. If the webpage gets refreshed for whatever reason (say, you accidentally pressed the button and locked your phone screen), the conversation with the customer service rep would end immediately, and you have to wait for the next rep to answer your chat and start over.
During the attempts to communicate with customer service via chat, I got an automated email that rebooked me for a flight the next day, without any hotel or taxi coverage. It was somehow booked in the midst of a work day. Nobody asked me when I can fly or offered me options to choose from. I could not miss work that day.
The chat customer service representative required proof of my work schedule to rebook. She declined to reschedule me unless I provided proof of my work schedule. She would not accept a screenshot of my Google Calendar as proof that I'm working 9-5 on a weekday, and wanted a pdf instead of a photo. You cannot easily export a calendar into a pdf on a mobile phone, and you cannot do anything on your phone without closing the browser on your phone for a moment - which would refresh the page, and terminate the chat with the customer service rep.
After many persistent attempts, I finally managed to get the flight's cost reimbursed, but not the Uber to the airport. I took the XPT interstate train instead, which is a public service. It always leaves on time, and while slow (11h overnight ride) - it's a much better service overall. The staff are nice and genuine.
I recommend on avoiding Jetstar flight, unless you're unemployed/retired and have no time restrictions whatsoever. But if you need to get from point A to point B on the time and day stated on your ticket, then perhaps consider other options.