Will work out far cheaper for some commuters who work "irregular" hours.
Taking as an example a commute I used to do, Pendle Hill to City, shift was 0600=1400, and using current fares.
Single is $5.00, return is $10.00 (not eligible for off-peak return), weekly is $40.00.
Under Opal, off peak one-way will be $3.29 each way, two journeys per day coming to $6.58 per day. After four days, eight journeys would have been made for a cost of $26.32, all subsequent journeys (including bus, ferry and light rail) will be free, a saving of $13.68 per week.
A yearly Pendle Hill to City is currently $1600.00, but since I normally go overseas or interstate for my holidays, it is really only useful to me for 48 weeks. Under Opal that will be $1263.36 a saving of $336.64, and that is before we factor in that sometimes on weekends I went to the footy by public transport outside the coverage aree of my weekly, meaning I had to pay for extra fares which will now be covered by the free trips on Opal.
So it can be a winner for some.
[EDIT TO ADD:]
Just spotted the following on the Opal website:
During the Customer Trial you should only use your Opal card if you start and finish your journey at one of the 10 Eastern Suburbs Line and City Circle train stations, or on the Neutral Bay or Manly ferry service.
If you tap on at a Customer Trial station but travel to a station not active for the Opal card, a default fare is deducted by the electronic ticketing system.
Given I live in Katoomba, which is in the maximum fare band, what would happen if I tap on at a Customer Trial Station, with the intention of travelling to Katoomba, and Transits or Police come through checking tickets, would I be liable to a fine?
Sure, they probably won't have the Opal scanners (particularly on the Blue Mountains line) but if a fine is issued, would there be grounds to challenge the fine in court? Considering that with no "tap-off" facility at Katoomba, the default fare is charged, and this would be provable in court by production of the Opal statement as having paid the fare for the journey undertaken.