Just got back from seeing this, being a fan of mysteries, I enjoyed the heck outta' this!
Good characters, writing and just the right dash of humor, it was all and all a very enjoyable film. As others have mentioned, it's best seeing un-spoiled, especially since it doesn't take long for some things to get turned on their head.
An count me in the boat of wanting more Detective Blanc films, and Rian Johnson stated that if the movie does even ok, he'll make more of these films in a heartbeat. Considering the film made double what was projected opening weekend, I'd say it's already done more than "ok", so I think this bodes well for seeing Mr. Blanc again!