You could run out of superlatives when reviewing this awesome series. It's simply the best "cop" series around at the moment. I'll review it on the assumption that you've not seen the first season, but if you have, you know what to expect - except this season gives you even more.
Criminal Minds centres around the BAU (Behavioral Analysis Unit) department of the FBI, and the small team who work there. These profilers analyse the evidence found at crimes - primarily murders, but sometimes kidnappings, arson, etc - and use it to construct a picture of the perpetrator. This show differs from all the other "cop shows" in that it approaches it all from a completely different angle. Where CSI, etc, look at the crime and follow that trail, the BAU's only interest in the crime itself is what it can tell them about the individual/s. And it is absolutely fascinating.
Mandy Patinkin (made famous playing Inigo Montoya in The Princess Bride) plays Jason Gideon, who is, without a doubt, the best character one of these shows has ever produced. He's supremely intelligent, charismatic, perceptive and has more empathy than most characters we now see on tv, let alone on a show of this nature. He's honest, centred, sardonic, and has more integrity in his little finger than Gil Grissom and Columbo combined. In other words, lots. And lots.
Gideon is surrounded by a group of people who mesh incredibly well - the chemistry fairly crackles off the screen sometimes. There's Dr Spencer Reid, a shy, gentle, slightly socially inept genius. Trawl the interweb and you'll discover that most CM fans rate Reid as either their top or joint-top character, and it's an accolade that's well deserved - he's delightful, notwithstanding what he goes through in season 2... but we'll come to that. Derek Morgan in any other show would be the "muscle" of the group - only, CM has managed to create characters that are deeply nuanced and fleshed out, so while Morgan is the most likely to kick in a door or tackle someone to the floor, he's also kind, thoughtful and measured. JJ (played by AJ Cook) is the beautiful blonde who women ought to abjectly despise... but she's loyal, and tough and vulnerable and she's a lovely feminine counterpoint to what is, typically, a fairly masculine genre.
Without giving too much away, we are introduced to a new character called Emily Prentiss, played by Paget Brewster. You may recognise her from her brief stint on Friends as Kathy, the girl Chandler stole from Joey in season 4. She's a welcome addition - warm, honest, witty and loving. Aaron "Hotch" Hotchner (Thomas Gibson, of "Dharma and Greg") is the guy in charge of the BAU, and he's everything you would want a leader to be. He will always do the right thing, by the victims and by his team. He runs a tight ship, and he rarely smiles, but the team would be lost without him. Finally, we have Penelope Garcia, who brings so much sunshine to the show. She's the computer genius who is able to hack any computer and find any information necessary, and she's a big, blonde, geek-chic, idiosyncratic ball of polka-dot and wig-wearing loveliness. All of the characters are given the opportunity to flex their comedy muscles, but it's Garcia who brings the humour to the BAU most frequently.
Three of the main actors - Brewster, Gibson and Patinkin - all made their names in comedies, which will give you an idea of the comedy calibre of CM. It's nothing overt - but it has some beautiful one-liners and dialogue which will make you laugh out loud. This is a nice touch, necessary even, as the scenes which show the crimes taking place, and the aftermath, can be relatively graphic. But, more than that, the writers' ability to create dark, twisted criminal minds is astonishing sometimes. In season 2, you meet one man in particular, Frank, who will make your skin crawl and the hairs on the back of your neck stand on end. He's the greatest anti-hero since Hannibal Lector and the cerebral stand-off between he and Gideon is beautiful television.
We are also introduced to a terrifying, almost unrecognizable James Van Der Beek who kidnaps and tortures one of the main characters - and yet even while you fear him, you'll pity him and want things to be ok for him. In that double-episode, as with every other, Criminal Minds will grab you in the first minute, and keep you on the edge of your seat until it ends. In fact, perhaps one of the greatest strengths of this series is that it really does go deeper in terms of examining why humans do what we do. The focus is on the people (both victim and criminal) psychologically and emotionally, rather than on the crime itself which, after all, is inanimate. It's disconcerting to discover you feel sympathy for a seemingly psychotic murderer, but in places, we see what made someone turn into what they became, and it's hard not to feel for them - that empathy is a testament to the quality of writers of this programme (who, sadly, as I write are on strike).
To encapsulate all of that into one brief paragraph, this show is unbelievably clever, witty and entertaining and I can't recommend it highly enough. I was about to say its lead characters are its greatest triumph, but then I'd be doing its villains and plot-lines a disservice; and if I were to specifically mention those three, that would imply its direction is somehow lacking, which it isn't. Criminal Minds is borderline flawless, whichever way you look at it. If I ever sprout Garcia-like skillz, I'll hack Amazon so I can give it more stars, because it thoroughly deserves them.