I just got this as an update to my other version. I agree with the previous reviewer that there probably isn't much in between the two editions, but my old book was pretty dog-eared, and there are some nice updates to the new one, including some details around the trail centres in the area. If you are a mountain biker who is used to riding trail centres, by all means use these as a starting point for your riding in the Lakes, but I would also really recommend the trails that are in this book.
The rides are well described, with easy to follow directions. You can also get a very good feel for what the ride will be like from the notes, and also the map. E.g. you can see how much road is involved (usually only country lanes), and get an idea of the amount of climbing / descending you would do from the altitude profile of each route. Altitude is a big indicator in the Lakes, as either way - up or down - can be pretty challenging, especially dependent on the terrain! Yes, you could pick some bridleways on a map and create your own route, but here all the hard work is done for you and you can just get on and enjoy some of the best riding that England has to offer IMHO.
The size of the book is also really handy, and you can just slot it into your Camelbak, or jersey pocket. I sometimes photocopy the map / directions and have that in my pocket with the book in my pack as backup. The great thing is that there are just enough directions, not loads so you struggle to follow.
I have an ambition which is to ride all the routes in this book, starting ASAP!