Sorry for the late reply, I missed this somehow.
I've got a few thoughts about it. Firstly, I think the article falls down as it's trying to cram too much into the space available. There are a lot of techniques included that could have done with coverage in greater depth, a two part feature would probably have been better.
What I like about the model - the front is nicely done, with subtle streaking from the places you'd expect. The fibreglass roof panel is very nicely done indeed and was one of those 'why didn't I think of that' moments. I shall be using that technique on the next 33 across the workbench
I also liked the grime pattern on the snowploughs. The grime along the base of the body and up the sides looks close, as seen here:
http://www.flickr.com/photos/beechwoodp ... otostream/
but it doesn't quite work for me, and I can't quite put my finger on why.
The rest of the roof doesn't convince me, I don't think it's faded enough compared to the treatment on the sides, or dirty enough. The underframe doesn't look oily enough, the dirt is a little too light. Other than that (and the paint finish as already noted) it's a very nice model.
I think it may come down to familiarity with the subject, as the Bedford and pallets in Cynric's link are the dogs bo**ocks!