I have to say that I like Games Workshop models. They're well detailed and good fit. One thing I hate about them is RIVETS ("rivets" is not appropriate form). I want to remove almost all of them.
Another annoying things are ubiquitous W40K characteristic features: eagles, skulls, purity seals etc. They're everywhere , even on tracks. For example , this is rear panel with so called "chapel of god in machine":
It's really well molded but totally incongruous. I'll remove it and put a styrene piece on this place.
Rivets had been already removed from turrent and cannon. That's how it looks now: