How bad is it? It's about the same as "Ghost Ship" - quite bad - but better than "Haunted Boat."
Should you see it? No.
Abandoned boat has a rubbery lizard monster on board, which is supposed to be Quetzlcoatl (misspelled in the film), the Aztec deity. The film is hopelessly padded, particularly with naked scenes of Krista Allen (who also is quite padded). There's no suspense, no characterization, no production values, just a surprise ending that's cringeworthy.