Their website is easy to navigate, allows you to book a flight and manager it afterwards with great easiness.
Prices are super-cheap if you book flights without check-in luggage, just hand luggage. In general, even if you have check-in luggage, pricing is very good. Prices go up, also, depending on hours of departure, the most inconvenient being the cheapest. But you expect this to be the case, no?
The planes are as comfortable -or uncomfortable- as any other plane you take if you fly economy class. Yes, a tin of sardines, not good for tall people, medium people or small people. Still, OK. My experience has always been excellent regarding punctuality within Australia. It might sound superficial, but I love the crew uniforms and the mix of colours that the airline uses; I think they give a serious but trendy image of the company.
The crew are efficient and very helpful at organising the on-board luggage in the cabin, which can be tricky, because everybody seems to bring fully packed mini-not-that-mini hand luggage. Me included!
You need to pay for your meals and drinks on board. However, Jetstar flight meals are tasteless, tiny and overpriced; nothing you would want to spend your money on, unless you buy chips or nibbles. However, you can eat before boarding and/or taking a sandwich, cookies, nibbles and (not smelly, please!) food with you. If you are flying domestic, don't waste your money on their food.
My main complaint about Jetstar would be that the crew is matter of fact, a bit pushy at times, and not that smiley. They do a great job, but a bit of more friendliness wouldn't hurt anybody. A final thing that annoys me a bit is the fact that, at least in Perth WA, we usually get to/from the plane from/to the airport through the tarmac, up/down steep stairs, luggage in hand, instead of using one of those covered jet bridges that make a whole of difference.
Jetstar Australia is a decent low-cost carrier that does what one could expect from them. I'd rather flight with Jetstar than with Virgin because, for similar or identical prices, you get better service and a more caring and efficient crew. That is my experience. However, I think, overall, Qantas is still cheaper for domestic if you take into account what they offer for their pricing.
SOMETHING TO BE AWARE OF
Whether you book through Jetstar's own website, Expedia or through any other online booking site, Jetstar will charge you, just because nobody is stopping them, 7+ bucks in fees just for paying with your debit/credit card, which, according to new Australian legislation is abusive and even illegal. I recently booked a trip that has the departure with Qantas and the return with Jestar merely for schedule reasons, and Qantas charged me only 2 bucks for the credit card payment. Really, this sort of things unnerve me and the law should prevent this from happening.