While it may not be the case with Jennifer Aniston you'll usually expect to see Kevin Spacey and even Colin Farrell in a better movie than Horrible Bosses. It's a comedy with a bit of a criminal flavor but the funniest thing in the film is the stupidity of some of the characters. There are people that find this movie to be surprising and with lots of twist but I cannot second that statement. There are small twists here and there but the bigger picture is pretty clear from the beginning and any occasional twists and funny moments are only enough to keep Horrible Bosses not so horrible as the bosses in it.
The movie is about three friends that hate their bosses for different reasons. Nick Hendricks (Jason Bateman) hates Mr. Dave Harken (Kevin Spacey) because Harken heavily exploits Nick, denies him a long overdue promotion and eventually blackmails Nick in order to keep him in the firm. Kurt Buckman (Jason Sudeikis) hates the new boss Bobby Pellitt (Colin Farrell) who unlike his father before him does not appreciate Kurt's work, uses drugs and he's not mentally stable. But Kurt actually likes his job. Finally, Dale Arbus (Charlie Day) hates Dr. Julia Harris (Jennifer Aniston) who constantly attempts sexual abuse on him and similarly to Dave Harken blackmails Dale with a former charge of child offending so he does not dare to quit. Thus, being unable to leave their jobs, the three friends decide to kill their horrible bosses.
The premise of the plot is not the most standard one but it is somehow limited. You wouldn't expect that our "good" heroes are going to become real murderers just to get rid of their superiors. Many of the situations are forced and the narrative while not fully predictable in details from the very beginning leads to the only logical outcome at the end. And apart of the unpredictability pointed by other reviewers, I cannot find also a lot of dark humor in Horrible Bosses (check Kind Hearts and Coronets for huge portions of it) but it's always a matter of perception.
The cast is interesting and it offers bigger names for the supporting roles while the leading parts are assigned to less famous actors. Kevin Spacey makes a good performance as Dave Harken but his character is annoying as pretty much most of the other individuals in Horrible Bosses. The exaggeration in the portrayal of both the bad and the good guys actually makes the story and the characters in particular hardly believable although the performances are not bad on their own. It also hard to believe that Mr. Harken could cry at all but you'll see him almost doing it in one of the scenes and this practically ruins the already depicted character.
Objectively speaking, Horrible Bosses has a few funny moments and some potential to be appreciated by a certain group of (teenager) moviegoers. It is definitely not a must-see film and it does not worth seeing this picture in a movie theater but you could take a look at it if you have nothing better to do at home some day.