This a very clever book and very fun to read. It's fun to see all the important silver age marvel counterparts in this older time period especially for those who are familiar with the older character/stories. The foreign sounding names are nice touch. To give an example of how modern marvel characters fit in this time period I'll highlight a few of my very examples. Nick Fury is a spy for Queen Elizabeth, Daredevil is The Man Without Fear a blind but skilled bard and instead of the doctor Donald Blake as the counterpart of Thor, he is an old crusader.
Not only is the story by Neil Gaiman first rate, but the art is very engaging.
The background behind the story is very interesting. Neil Gaiman wrote the book in order to raise funds to in his court battle with Todd Macfarlane. Both have claims to the Miracleman/Marvelman character. So while the conflict is unfortunate because there aren't going to be any new Miracleman stories or reprints until it is resolved, it did bring about a great comic book!
I have one word of advice: don't bother with the sequels to this story. 1602: The New World is awful stretching the credibility thin and making a good idea very hokey. The Fantastic Four story isn't great, but it's a little better than the New World.
I am trying to catch up on all the Gaiman stories I have missed. This looked like a pretty interesting one; I mean how cool is it to re-imagine all of the Marvel characters in 1602? Overall it was entertaining. The story was excellent and the drawings fantastic. I am a new-comer to the Marvel universe and as such I think I missed some things that a more comic knowledgeable person would have grasped. At times I also thought the story line jumped around a bit too much.
Overall though I really enjoyed it. I would definitely recommend this is you are a Gaiman fan or a Marvel universe fan. Some of the ways Gaiman adapted the Marvel heroes to the 1602 time-frame were very interesting and creative.