Well, Will Ferrell has had his ups and downs, with perhaps more downs than ups. I personally liked "Everything Must Go" the best, but that just goes to show you what I like in a movie - not what Will Ferrell fans like. Clearly his screwball comedy must please a bunch of folks since he still does it.
This one - a rework of the idea that Watson was (or is) the real detective was done back in 1988 with Ben Kingsley in "Without a Clue". That was genuinely funny. This movie on the other hand is one joke told over and over. Holmes (Will Ferrell) is full of himself, and spends all of his time preening and lost in details that don't mean anything, while Watson figures it out and tries to get Holmes to get going.
I know when I really don't like a movie - I start to fall asleep, and have a terrible time keeping my eyes open. Oh well, 1 paw.