It's good stuff. The 5,000 mile/6 month guarantee from ExxonMobil is also a nice touch.
I've got it in my Camry now, and use it when I do oil changes for friends. No problems to report yet.
I'll be using it for the next 6,500 miles or so until my car's warranty runs out at 60,000 miles, then I'll switch to Mobil 1 Extended Performance. With M1EP's 15,000 mile OCIs, I'll save a bit of money compared with Mobil Clean 5000 and a new filter every 5,000 miles. That said, I'd have zero problems with using Mobil Clean 5000 if M1EP wasn't available.
It way better than QS and honestly I think it's the best dino for price! Look at the "New Sherrif" thread and compare the numbers of all dinos. MC5K came out on top.