Fraid I use the flick method with Francis Rose, in general the art work is very good, but yes there are always variations. I find id books with photos in really hard to use because you can't see all the parts you need to whereas with a drawing the artist can get all the relevent bits in.
Similarly id'ing from a photo is also hard, I find writting a brief description as well makes all the difference.
You've just got to find a book you are comfortable with, some of the ones that divide plants up by colour rather than family can be really good, especially to someone who is just curious rather than wanting to be scientific about it all.
And there is always the WABers for when your stuck, it's what we all like doing