I work at a Holden dealership and have driven the new Colorado a fair bit.. They are alright and quite comfortable.
They seem pretty equal to the previous model aswell. The RC Colorado (my old man has one of these)
The new model has a longer body frame and all new engine design. Gearbox drivetrain etc. but just doesn't seem as comfortable.. It has a more spacious interior. But in my opinion it's a bit to spacious.
The old mans mate has the new ford ranger and that is pretty tough! Haven't driven though so its a bit hard to compare.
Hope this helps