I've read 1,2,4 and 5. Yes they are quite entertaining. Some of the adventures are a little bit of stretch but I come away having enjoyed them. Although its been awhile, Dourado, Cibola, and Icefall were very good.
Has anyone read the Lincoln Blackthorne books by Geoffrey Marsh? Very Indy/James Bond-like. Some crazy macguffins. I really enjoyed them!