With the exception of the first month, my Presto Card has worked flawlessly. I guess I've been lucky.
A few things you have to remember:
- Try to avoid tapping your Presto Card in a wallet. I've had issues with that where the reader entering the bus read, but the driver side indicated error. If you bring your card out separately (or put it in a separate pouch in a wallet so you can easily take it out), it never has any problems.
- The TTC hasn't fully implemented Presto yet. Please don't judge Presto simply by what the TTC has, as that's unfair compared to the true extent a la GO Transit and other suburban transit systems.
- Don't reload your Presto Card unless you're absolutely certain you will use your Presto Card in the 30 day window (or better yet, 7 day window). That's where many of the reloading issues occur.
I've had a Presto Card since 2010, and I've only had one problem with it, which was related to my first point. Once that was solved, everything with my card worked as perfectly as expected, and coming from someone who visits multiple transit systems, the fact I don't have to fiddle around with change makes this smart card very beneficial to me.