Lie to Me is a very interesting series, with a lot of humor and a very interesting premise in my opinion. In addition the 4 Cast members all play their role very good and add to the show's freshness.
Tim Roth (great as always!) plays Dr. Cal Lightman, a human lie-detector, who's able to detect any lie from people's body language. That ability comes in handy when catching criminals, but it also provides him with the misfortune of always knowing when someone is not honest with him, sometimes leading to unfortunate situations. Lightman is a cynic and unpleasant character, who's willing to do anything to find out if someone is telling the truth or not.
The series also features a strong supporting cast, including Kelli Williams as Dr. Gillian Foster, whose husband is cheating on her, a fact everyone of her colleagues is aware of, except herself. Brendan Hines' character is always telling the truth no matter how embarrassing and Monica Raymund starrs as Ria Torres, who has the natural ability of seeing if someone is lying. That often leads to conflict with Lightman, who refuses to believe her ability is as accurate as his, since he needed years of training, while she was just born with her talent.
Yes, there are parallels with other series, especially "The Mentalist", but those are pretty much limited to the ability of the main character being able to detect the truth from people's movements and voices. Besides "Lie to Me" is focused on the science of detecting lies, something completely ignored in "The Mentalist". For example, it will take a person who's telling the truth longer to respond than one who's lying, because the one telling the truth needs to think about the answer.
The only real flaw after 5 episodes is in my opinion that not enough character history is provided. We literally don't know anything about the characters, except a few details. I have no doubt we'll eventually find out more, but it's about time they start. All in all, the series is great fun and entertainment, and maybe you'll be able to pick up one or the other lie in the future, thanks to Lightman's group.