"Lost" has a crazy cast. My opinion on the characters (listed in the order I found them on IMDB):
Sayid Jarah - Awesome. He's one of my favorites. Making one of the characters Iraqi in a post 9-11 world was awesome.
Jack Shepherd - Sucks. He's temperamental, tyrannical, has the emotional maturity of an eggplant, whiny, and inconsistent. One minute he's a skeptic demanding proof for the weird crap on the island, the next minute he's embraced the idea of "destiny" without any transition. Apparently the character of Jack was supposed to initially die in the pilot episode. I wish they'd done that.
Hugo "Hurley" Reyes - Okay. He's the "everyman" and he's not some square-jawed hero. The character has gotten some great moments in as being an astute observer and being able to talk to the dead. Unfortunately, the writers feel the need to make him a cliche as a "dumb fat guy" and that bugs.
James "Sawyer" Ford - Above average. He's a fairly complex character as the con-artist with a literary side to him. I think this character would have been a better lead than Jack.
Sun Kwon - Awesome. My crush on Yunjin Kim aside, the character of Sun has dimensions to her that I've liked. There are moments that she's fipped into "WTF?" territory, but every character has. Given I'm totally in love with Yunjin Kim (okay, maybe just infatuated...), I expect that's given me a bias. Kim apparently tried out for the role of Kate, but was considered a "bad fit" for the role. So the writers created the role of Sun for her. Yeah. I'm happy.
Kate Austin - Meh. Evangeline Lilly is quite striking, but I find her character less-compelling. The outlaw lady should be more interesting, but the writers just can't seem to figure out what to do with her beyond make her the prize for Jack and Sawyer to fight over. Kind of stupid. She's supposed to be kind of tough and badass, but her portrayal in the story makes her seem kind of whiny and ineffectual.
John Locke - sucks. He was originally among my favorites. A crippled man who could suddenly walk, Locke was mysterious and had all these mad survival skills. He just embraced the island as a mystery and ran with it. Then he got weird and inconsistent. One second the writers had him a fanatic of the island's mystery. The next he was a skeptic. And he'd just arbitrarily decide he "knew" what the island "wanted/needed" without any real justification. He's since gotten weirder and more whiny. Hate the character now as much as I hate Jack (or more!). Terry O'Quinn - the actor - is aces in my book though. The guy rocks!
Jin Kwon - Above average. Sun's husband is played by Daniel Dae Kim, a veteran of many a sci-fi classic like "Crusade". Thus I have a soft spot for Mr. Kim (no relation to Ms. Kim). The character was initially a bit rough, but they've done some interesting stuff with his backstory up to the point when everyone got separated. Now... he's kind of bland.
Claire Littleton - Above average. The secret half-sister of another character, Claire was the very pregnant young lady who gave birth to the child Aaron. I always liked the character and was startled when she was suddenly shifted off the show.
Charlie Pace - Sucked. A substance-abusing rocker with weird mood swings. I hated Charlie for reasons that had less to do with the character and more to do with similarities the character had to people I know in real life. Monaghan is a good enough actor, but I must admit I cheered when Charlie met his end.
Ben Linus - Awesome. The man I love to hate to love to hate to... This guy is just aces. Pure gold. Can't get enough of him. Can't figure out why someone hasn't shot him in the head.
Michael Dawson - Meh. "Waaaaalt!" The writers really didn't know what to do with him. A shame, 'cause Harold Perrineau rocks.
Desmond Hume - Awesome. Another favorite, Desmond wasn't on the airplane that crashed on the island. He got there another route and has this weird but awesome connection with Penny, the daughter of Charles Widmore who... oh it gets complicated. Desmond was a mystery and had a crazy intensity that was just neat. The writers clearly haven't known what to do with him, but at least they've given his story some happy moments.
Juliet Burke - Average. The "Other" who went over to the good guys, Juliet's story was pretty interesting. I just wish they wouldn't have her be the consolation prize for whomever isn't making time with Kate.
Shannon Rutherford - sucked. She's dead. Good.
Walt Lloyd - meh. Kid on a show. The actor made the kid really interesting, but the writers clearly didn't know what to do with him, so he's gone.
Daniel Faraday - Awesome. The scientist who came later to the island, Faraday had the potential for answers. Then the writers did something that has made me rather angry with them.
Miles Straume - Awesome. The weird guy who - like Hurley - can interact with the dead. Miles has an interesting backstory and has been a fascinating addition.
Mr. Eko - Awesome. When they killed Mr. Eko, it was as though they killed a part of the show.
Boone Carlyle - Sucked. Glad he's dead.
Ana-Lucia Cortez - Good. It was a shame they killed her off.
Libby - Good. See above re: Ana-Lucia.
At this point I'm getting into minor characters and I pretty much like all of them.
Why do the minor characters always rock? Hollywood, you suck.