If you are an existing AGL Energy customer, this seems like the cheapest 100/20 NBN plan at the moment. If you aren't with AGL Energy, this probably won't be worthwhile for you (unless their Energy plans are also cheaper than your current provider?)
nbn modem/router not included. BYO device.
Doesn't appear to have any termination fees, so you can leave any time without penalty. (Looks like previous versions of this deal had a $220 early exit fee, but I can't see any such fee in the current T&C's).
EDIT If you do sign up and need CGNAT disabled, you have to call their Tech Support on 13 12 45 and ask for a "PUBLIC IP". I just did this and it took 5 mins all up.
MORE is cheaper if you are with CBA.
$56.4 for 12 months.