I flew into/out of ONT last month when I went to visit my aunt. It's about as hassle-free as an airport can be nowadays. The time between the boarding door being opened and picking up my checked bag was under 10 minutes.

On the return, the time it took to check in at the kiosk, hand over my bag, go though TSA, and walk to the gate was less than 10 minutes, too. The distance from the AA ticket counter to the AA gates is probably less than 100 yards.

As noted, there aren't any lounges. And, the retail and dining options are limited. But, if you flights are on time, those things aren't all that important.