I just received my Haynes manual for the MINIs (see this weblog entry)!
The Haynes manual makes an interesting comparison with the Bentley one which came out last year; the Bentley manual is much more expensive ($100 compared with less than $30) and it shows – at least in the quality of the paper – the Haynes manual is printed on very low cost non-white paper, with a rough feel; the Bentley is pristine smooth & pure white.
But in other respects, the Haynes wins easily. I may be biased to Haynes having used them regularly in my earlier fix-my-own-car years, but the contents of the Haynes manual seems to me to be much more useful. For example, they have taken the trouble to re-draw the electrical schematics so that you can actually understand them – see above (Bentley simply re-printed MINIs own wiring diagrams).
I freely admit that I don’t own either the Bentley or Haynes manuals because I plan to work on the car – they are just part of the collection – but if I did need one, the Haynes would win. Three times less expensive, clearer wiring diagrams and actually the less quality paper is probably a benefit – you won’t worry so much about dirty fingerprints getting on it!