We live in San Marco and had to drive over, and took it with friends who also don't live in Riverside. However, it was very convenient as we were meeting them over at Cork. I expect there's less interest from non-Riversiders to use it, especially before barhopping hours really set in. Our trolleys were consistently packed after 11 pm or so, much more so than when we first got on.
Several people I met were thrown off by the payment. Some didn't realize you could ride without a pass by paying per-ride (and some didn't have exact change for it anyway). Others I met didn't know about the day passes or that you couldn't get them on the bus (or that buses don't usually take credit cards. Oh, Millennials).
However, I think one of the biggest issues is the one you can't control: the rain on Saturday. Though it eventually cleared up I'm sure that put a big damper on peoples' plans. I was over at Bold City and it was pretty slow for a Saturday. I expect if there was only a small dip, that's why.
Thanks for all you do, Mike.