The vast majority of those using the NBN are happy! For most the NBN is fast, always on, and reliable. We have all heard the horror stories, but they are truly few and far between, after all, it is not in your ISP's best interests to offend customers.
Entry level 12/1 (either as good as or better than your current ADSL connection)
Mid level 25/5 (high speed, much faster than most could achieve on ADSL)
High speed 100/10 (not available to those on fixed wireless) for power users
Start with what you can afford, and remember that you can always increase your plan, but to reduce there may be a penalty.
The entry level 12/1 plans are quite fast, more than adequate for day to day use and watching Netflix or similar, but at peak times performance can drop significantly to speeds of less than 5Mbps, and if you have multiple devices you may wish to move up.
The mid level of 25/5 should suit all but the most bandwidth hungry and is usually only a few dollars more. You can watch multiple movies simultaneously on multiple devices.
When you get the NBN you also get a free "phone line". Instead of plugging the phone into the phone socket, your phone will get plugged into the back of your new modem, and it will work exactly the same as it does now. At the time of connecting, tell your provider you wish to keep your existing phone number and it will be transferred at no cost.
On the basic plans you still pay to make phone calls (although often at lower cost than your POTS (Plain Old Telephone Service) connection), but for a little extra you can get unlimited plans that allow calling mobiles or landlines anywhere in Australia with no additional call charges.
It doesn't matter who currently provides your internet. When the NBN becomes available you can use any ISP you wish. This will be especially helpful to those who previously had no choice because there were no available connections for other providers in the exchange, and for those who could not even get ADSL, you're going to think it's Christmas :-).
If you are happy with your current service provider, by all means stay with them, but at least you now have the choice. Be aware that if you are using an email address hosted by your existing ISP (eg firstname.lastname@example.org, email@example.com, etc) you will need to take steps to get a standalone email address or change to one of the free providers like gmail, but that is easy!!
You will receive calls from people purporting to be from Telstra and others claiming that if you don't make the move you will lose your home phone and internet connection. Ignore the calls.
From when the NBN is available you will have 18 months to choose what plan and which provider you wish to use, this is extremely important if you are currently under contract but wish to change provider. Just wait until the contract expires.
If you wish to choose an ISP, or ask questions, look up the phone number and ring them or simply browse the web and read the offers.
The NBN as rolled out to us is not the best available connection option, but it is more than adequate. I have been on fixed wireless for over 2 years, the connection has been fast and reliable, astoundingly reliable compared to the Telstra, Vodafone and Optus 3G and 4G offerings, and dramatically cheaper.
Most people will be offered Fibre To The Node and will have the choice of 3 speeds (I was only offered the 2 lower speeds).
At the time of writing, 29% choose 12/1, 54% use 25/5 and just 17% choose the higher 100/10 speed.
We could have had the best, the gold plated NBN, the NBN with gigabit speeds (1000/100) through Fibre to The Home, it would have cost significantly more and almost certainly taken significantly longer to get here and yet the vast majority would not have taken advantage of the increased speeds available because it costs too much.
Enjoy your new connection, if it is not good enough for you, relax, 5G is coming to your next phone and it could blitz the NBN speeds :-)