The moral of the story, then, is "look at them all before you buy". I've posted at considerable length on this before so I won't repeat myself, but in brief I rate Simpson & Day as the least good choice for a beginner. Some people claim that the illustrations are better than alternative guide A/B/C, but it's easy to find particular examples where the opposite applies. You can do this with any of the guides.
There was an example a while back where George posted a picture asking for help with ID and Moorcombe was the only guide which clearly nailed it. (A young White-gaped Honeyeater, I think it was.) Does that mean that Moorcombe is the best? Certainly not: for every example where Moorcombe is the best, there is another one where Pizzey & Knight is superior, and another again where the old Slater guide shines, and yet another where Simpson & Day is best.
Overall, I rate Pizzey & Knight and Moorcombe jointly in first place, and it is nearly always one of those two I reach for first, and I regard the other two as good but flawed: Simpson & Day for its very uninformative text, Slater for the infuriating way it still has lots of birds in the wrong order, even in the latest edition, and it takes forever to find anything.
You rate them the other way around, Zuiko. That's fine. Indeed, it's a very good thing - if we didn't all have different feelings about what makes a good field guide, there would only be one guide on the market, and none of us would have the benefit of being able to select from amongst four excellent books - five if you count Flegg.
Pick the guide you like best and good birding to you!