Disclaimer: I'm not a regular commuter, I walk to work. I live close to a train station. I don't work for Opal/Cityrail.
I like it. I catch the train now more often than I used to. Instead of driving to the shops, I like taking the train and back, taking advantage of the 60 minute transfer. All for $3.30, or $2.31 off-peak. Granted, I can't bring as much shopping back, which may be a plus I guess if it limits how much I spend. But it saves me petrol and looking for parking. I know doing a 60-minute round-shopping trip isn't for everybody, but it works for me as a single guy. At $7.60 or $5.00 off-peak return for paper fares (at a minimum), it was tipping the favour towards the car.
On the Sundays I'm not working, I always think of ways to make full use of the $2.50 daily fare. I intend to catch the Manly Ferry and go to the Blue Mountains in the near future.
Cons: One Sunday, it ate into my 'profit margin' when I had to catch a 4XX bus without an Opal reader and had to pay a normal fare in addition to the $2.50 daily rate. And most times, I'm wary of not catching a bus because of the dangers of not tapping-off. It's so easy to forget, but I'm lucky it didn't cost me anything extra when it happened on a Sunday.
It's marginally better if you're doing consistent journeys on a regular basis.
If you change modes (bus-train-ferry), travel irregularly, or use long term tickets, you're getting shafted