The Good: Simple and effective.
The Bad: Only thing i can think of is the two screws that hold the top guide on are a little long if you don't use the spacers which could cause clearance issues with some frames. I'm running a tr450 and its fine though.
Well been running it for a year and a half without a single issue. Its been superb. Was the simplest chain device i've ever fitted which was brilliant. Overall, couldn't be happier, and to get it at the price i did i'm still smiling about it. :D