Seems like a good deal.
12 months at $49 per month = $588
Less the $250GC, per month rate = $28.16
Unlimited calls etc.
Not sure if you can get a $10 monthly port in credit with Telstra or not. If so, bargain.
N.B. This plan does not include 5G
UPDATE - THE PLAN MAY NOT INCLUDE ANY CALL ALLOWANCE (sorry). It seems like that JB website has now updated the link for Terms and Conditions. Initially they had two links, that one I clicked said call allowance. But that link is gone now. I'll keep checking.
There's no way I would pay this kind of money for this deal. Much better options available with different providers