I'm turned off of Isuzu. Even if it was offered here I wouldn't want it. My wife's Isuzu Rode was poorly built with shoddy materials and bad engineering. Isuzu kept issuing recalls (probably forced by the NHTSA) but NOT honoring them. Even if they have improved I would not be ready to trust them.
If it is indeed a badge-engineered GM, which is pretty likely, I'd still be hesitant...not only will it be subject to Isuzu's post-sale service and support, but as much as I'm a GM fan I think they've been slipping in the past few years.
Here in Thailand the Isuzu is a real winner ... I have the 3Ltr 4*4 called the V-Cross (Auto 5-speed). Now over 40K Kms in two years and no problems at all.
The fuel consumption has been pretty good, getting 16-18K/Ltr on a run, mind you that's driving at about 80-85Km/Hr.
I've recently blanked the EGR and although it is much smoother and quicker in the 800-2000rpm range it seems to be using more fuel. A lot of the last tankful was in Bangkok traffic and only I got 12.4Km/Ltr .
I have just changed from Shell Fuel Save Diesel to Shell V Power Nitro Diesel (this costs here just under 33Baht/Ltr). Fuel Save is just under 30 Baht/Ltr. Also I have just changed the oil to Mobil 1 Turbo Diesel For Pickups 5W-40. Will see how things go.
By the way the Colorado has a different engine and also a different Auto Gearbox (it's 6 speed)
If you lived in Bangkok you wouldn't want a manual, unless you are a masochist! I bought the Isuzu V-Cross 3Ltr 4*4 Auto (in 2012)to use instead of a car. A 520d, which I previously had here is the UK equivalent of 100,000GBP. The truck was equivalent of 20,000GPB and the view from up there is really good and it takes potholes in it's stride.
Since blanking the EGR I don't get a good fuel consumption but it feels much nicer in the up to 2000ish rev range. Prior to blanking I could get 20Km/Ltr if I drove at about 80Km/hr.
No problems in 45000Kms ... well made ... reasonable ride ... am considering removing a leaf from the rear springs to soften it further.