I bought my Colorado 7 18 months ago with 9000km on the clock and nine months old. It replaced my bought-new 2011 Suzuki Grand Vitara. It is now sitting at 35,000km after two outback road trips. It is pretty much stock except for some decent-quality larger all-terrain tyres and iDrive.
It has been very reliable and hasn't missed a beat. It is effortless to drive and has plenty of power, overtaking anything including road trains is a breeze. On the open road with three adults, two kids and all associated luggage and fridge it averaged about 8.6L/100km. Daily it averages 11.5L/100km. The family find it very comfortable and it has good oddment storage. I am 6ft 2in and fit relatively comfortably in the third row.
Interior-wise, I don't like the round single-zone climate control in the LTZ, the LT's normal AC knobs look better. I like the simple uncluttered look about the dash and simple use of everything. Fit and finish could be better, although I have adjusted some of it myself. I made some soft armrests for the doors from high-density foam and pattern-matching vinyl. I have put some 'felt' in the gloveboxes and centre console to reduce the noise of things sliding around.
I started by looking at the Fortuner and Pajero Sport (Everest Ambiente was too expensive and too basic). The Fortuner was too small and the third-row design was a complete deal-breaker. The Pajero Sport was nice in all ways, but the lack of three rows in the entry level (didn't want leather), no height-adjustable passenger seat, and the way that the third-row seat bases fold up limits luggage capacity.
The MU-X was nice, but the (at the time) five-speed auto and engine didn't compare against the smoother and more powerful Colorado 7. I think it is underrated, and if you want a simple, relatively low-tech 4WD tourer, I would highly recommend it.
I would love to see easier access to the third row with child seats in place, and a standard rear locking diff.
We love this 4WD, and taking us on two awesome outback road trips, it doesn't mind corrugations as long as you let the tyre pressure down.