Outwardly, a magnificent piece of work; it bulges with superb artwork and it manages to cover an awful lot of ground. However, and as mentioned by others, there are a few errors involved which is never a good thing in any publication which calls itself an encyclopaedia. These seem to be the exception rather than the rule, though, and it's easy to forgive such things in return for the wonderful presentation and lay out. This is the only reason I give it 4 stars instead of 5, and I have to say I feel a bit mean about having to do so. I'd be happier giving it a 4.9999 rating.
That said, any comic fanatic should find it a joy to browse through the pages of this mighty tome and I certainly consider it money well spent.
Don't let a few silly technical errors rob you of an opportunity of endless browsing pleasure - If you're a Marvel buff you'll spot them easily and dismiss them with a tut and probably a grin and if you're not you'll never notice them anyway. You need to know there are errors, but you shouldn't let that put you off investing in this gorgeous piece of work.