Grisham is in a rut, that or he isn't spending enough time on his novels because this one, which starts off well, has a plot very similar to the Firm, ends really badly.
Kyle McAvoy and Mitch McDeere are almost interchangeable except for economic background, both brilliant law students, both hired by big firms, both blackmailed to do things they don't want to do.
The difference? The Firm is by far the better book as the ending is more conclusive, more fulfilling, and wraps the whole story and characters up. The Associate does none of this, leaving several questions unanswered, to such an extent, you wonder if a sequel isn't being planned, though this would be very un-Grisham.
All in all, good mystery, good plot to begin with, disappointing ending.