I'll probably regret saying this, but my Mk3 66 plate EX CVT, purchased new in August 2016 has covered a tad over 17000 fault free miles. Everything works as it it should and nothing has gone wrong.
Yes, the Atkinson cycle engine takes a bit of getting used to, but i'm prepared to accept that, in the interest of fuel economy. I can't give you the MPG over the 17000 miles, but the 'B' trip is current showing 7000 miles at 51.0 MPG.
My previous cars were an EX I-shift and a MK2 EX CVT, both good cars, but in my opinion the Mk3 is better overall.