
While the movie's "plot twists" are fairly predictable, the cast is engaging and the story itself is appealing. The newest member of the team, Ben Campbell (Jim Sturgess), is innocent but brilliant and is (predictably) corrupted by his success at card counting. His committment to the team is strengthened (again, predictably) by the presence of love-interest Jill Taylor (Kate Bosworth). The mentoring - he actually says "you remind me of myself" - of Professor Micky Rosa (Kevin Spacey) gets him in the game, but (again, predictably) eventually the student must challenge the teacher.
An entertaining movie based on a true story, 21 is a fast-paced film peppered with clever, snarky dialogue. The actors are well-cast, and give the performances one expects. The movie devolves from a unique and true story of the no-longer-possible exploits of a bunch of whiz-kids into a morality tale, but I'd say it's a good rental anyway.