I have rode it.
I actually find Colossus to be quite enjoyable. But as MG said it depends on where abouts in the train you ride.
For a smooth ride it has to be the front row but for a rougher ride nearer the back would be the best idea.
The only part of airtime that I have experienced is the bunny hop between the exit to the loop and the entrance to the cobra roll. The Cobra Roll is slightly rough wherever you sit in my opinion.
The inversions are a little crammed together. The 5 in-line twists are very good. They can make you slightly dizzy. The last in-line right before the break run is always a good one to catch you out as very few people know that it is there. It is also quite a good head chopper.
As already mentioned it does indeed need a clean up and a paint now a days, but other than that I find it enjoyable and a decent 10 inversion ride.