I've been using the parking reservations system pretty regularly for a while now and they seem to be smoothing out the bugs, or I'm getting used to it.
The economy lot reliably reads my license plate to let me in and out. The lookup is pretty quick now so there's often someone working out credit card payment in one of the other lanes and I can just roll up, tap the brakes, and it says "thanks, chrisl137!" and pops up the barrier while the other lane is still fumbling with cards.
The CTA parking is still a little iffier, but improving. I parked in P4 monday morning and they had booked it full enough that it was coned off and they had to have someone check my reservation manually before letting me through to the ticket dispenser/QR reader. That one still wants to see the QR code on the way in. It did read my license plate on the way out though - I was reaching for the scanner with my piece of paper and it recognized the plate and popped up the gate before I got it into the beam. I suspect they'll keep creeping up the pricing on the CTA parking until they don't have to have manual checkers at the entrances.