I am very pleased with mine.
Digitrax DZ126IN after rediscovering the Digitrax on-line manual and setting CV 57 to 5, CV 55 to 100 and CV 56 to 30. I'm sure I can do better with some more trial and error, but it's now running sweetly and, of course, it looks the bees knees. I hope this is helpful to others.
I should say that for a while I thought I'd got a dog, then I thought I'd better try it on DC (PP3 and two light bulbs in series!!) and it seemed to run smoothly. Never had this problem with Digitrax decoders on Hornby or Bachmann, so it would be nice if Hattons added a note about decoder settings, as suggested in an earlier post.
I am an average modeller, who likes to add detail to make my models believeable; I'm very pleased with mine for less than £100 (especially as it's a present from her outdoors!)
Chris