Sorry for the double post -- got caught with things here and didn't get back to my post.
To be a bit more informative: I've read pretty much everything I could lay hands on by Moorcock until the last few years (about the time of the final Pyat book, The Vengeance of Rome), and even then I have read a few, such as the graphic novel Elric: The Making of a Sorcerer. I keep meaning to get back and read those I've missed, but have not yet managed to dig down in my pile enough to get there. I've even fallen behind on keeping track of what he's been publishing lately, something I, as a collector of the man's work, really need to rectify.
One thing I would like to address is the ambiguity of that phrase (when it comes to Moorcock), "other work". With the exception of a few nonfiction pieces (and even here the distinction is questionable), pretty much everything Moorcock has written has been subsumed into the Eternal Champion cycle, really. He has included just about every major (and no few minor) characters he has created in that structure, and no matter what the type of book -- fantasy, science fiction, contemporary fiction, western, mystery, comedy, what-have-you, in one way or another it all hangs together -- much as (as I point out in one of those threads I linked to above) pretty much all of Cabell's work up to that time was subsumed into his Biography of the Life of Manuel. (Even some of his later work was at least connected to it, though not as "directly".)
Moorcock's themes have remained pretty much consistent, though his ideas on such have grown and he has examined many new aspects of these themes over the years from a variety of angles -- one of the advantages of having such a free structure as his multiversal Champion cycle being to allow what would be contradictions in just about any other form to be valid extensions here.
The problem, one which Moorcock himself has commented on now and again, is that, as what he writes is so varied and so disparate in "genre" or mode, large chunks of it are indigestible by many readers who are extremely taken with other aspects. I've encountered relatively few who can take the entirety of the cycle and either enjoy or at least appreciate the incredible achievement it represents. Even I have those I don't care that much for (though most of these are among his earliest works, when he was still a relatively crude beginner); though I do find points of interest in them all, and am enormously fond of the majority of it all. Moorcock, like Balzac or Cabell, has attempted the sort of unified structure which deals with just about every aspect of the human experience, and from a number of often very different perspectives as well as manner. When taken as a sum total, it is a breathtaking thing with a great deal to offer, but I would recommend anyone who approach it either seek out the particular type of story they like and leave the rest alone, or try to be open to such a variety in type, voice, and handling. If you are simply looking for the heroic fantasy romances, you're not likely to enjoy Some Reminiscences of Mrs. Cornelius Between the Wars (also known as the Pyat sequence); if you prefer sf, you are likely to be bored with such things as Lunching with the Antichrist or London Bone... or, as Baylor pointed out elsewhere, the Cornelius stories. But, if you can loosen up and approach each as a different facet of a remarkably complex structure, you will find riches galore both in ideas and often in sheer beauty of prose, as well as generosity of spirit.
Be prepared, also, to intensely dislike some of the main characters, even your protagonist. Karl Glogauer is often very difficult to like, while Maxim Arturovitch Pyatnitski (Colonel Pyat) is likeable enough in the Cornelius books, but in his own sequence is about as alienating a figure as you are likely to find... yet the latter (and the Glogauer book Breakfast in the Ruins) contain some of Moorcock's most elegant and even stunning prose, and are both bravura and highly controlled performances, and I highly recommend them to anyone truly interested in the man's work overall.