I guess I never commented on this. I read it in a short period as well, LawgSkrak, one or two days, and I still thought it was fairly lousy.
I wasn't as bothered as some by the level of focus on the antagonists - the German and the Japanese commanders were somewhat interesting, if conventional - but they did still drag. The bits with the Boukman weren't terribly interesting, however.
We did get the one scene with some actual archaeological technique, and that was welcome, but apart from that so little happened; just a lot of trekking through a single place without much in the way of action. (McCoy's Dinosaur Eggs is probably the model for an Indy narrative of this sort that does it well.)
The use of Mac was a major lost opportunity, without any effort made to flesh out a character with a lot of possibilities. I don't think it even took the opportunity to clarify whether he's a professional treasure hunter or archaeologist.
Perhaps the best that can be said for it is that it fills in a time in which we know little about Indy's adventures, and takes him to a locale in which we have never seen him in any fiction above the level of the comic books or Find Your Fate adventures.