If it isn't obvious, CLAMP seems to love their own work. The crossover manga of "Tsubasa: Reservoir Chronicle" and "XXXHolic" also includes plenty of past works.
Story: Syaoran is good friends with the princess Sakura. However, something crazy happens and Sakura passes out. Syaoran meets the witch Ichihara Yuuko, and she tells him that Sakura has lost her memories. Yuuko will give Syaoran the power to cross worlds and collect these memories, but Sakura will forget her love for Syaoran. Syaoran, desperate, agrees. So now he travels the worlds with the wizard Fai and the samurai Kurogane, who also have made agreements with Yuuko.
CLAMP somehow manages to make each world unique, so the story doesn't get repetitive, but this is obviously a character-driven manga.
Art: Any CLAMP fan will recognize their artwork at first site. The unnaturally long limbs and the like make for an odd-looking manga. I, personally, like CLAMP's style and don't mind the off-putting anatomy, but some may not. Backgrounds for the worlds look detailed, but the level of detail ranges from panel to panel. The chapter pictures are effing gorgeous.
One unfortunate thing is that CLAMP tries to draw blood. Now, I am more than aware how difficult it is to draw blood and characters being cut, but it's a little glaring how unrealistic it looks. It certainly could be worse, but it just looks... weird. But that's kind of CLAMP's art as a whole.
Characters: I said it's a character-driven story. It's a character-driven story.
(This picture should give you a pretty good idea of CLAMP's style.) Characters: Kneeling boy: Syaoran; sitting girl: Sakura; blonde-haired boy: Fai D. Flourite; black-haired boy: Kurogane.
Syaoran: He is willing to do anything (literally. ANYTHING) to save Sakura. His kindness is touching and, I don't want to spoil but, he gets so much better as the story progresses.
Sakura: Despite my automatic hate for anyone with the name "Sakura," I liked her... most of the time. She is pretty useless but tries to be much better than she is, which gets on my nerves. On the other hand, I would love to have her as a friend (am I allowed to say this after calling her annoying?).
Fai D. Flourite (but there are about 762 ways to spell his name): I have no clue WHY, but I loved him from square one. He always had a smile on his face, he was never mad, and he was so funny. But, please, do not make me spoil this... the temptation is too high already... Must. Stop. TYPING.
Kurogane: The polar opposite of Fai, he's rude, tough, and doesn't care much for human life. He is easily angered (which provides the humor aspect of the manga), and his dynamic with Fai is friendship. Unless you're a fujoshi. And I am one. I will stop typing now.
These are the main characters. Of course there are side characters; this isn't a one-shot or anything. There is development and there are backstories, but I do not want to spoil.
Overall: It starts off slow, and you may want to drop it, but keep reading. It really improves. I haven't read many of CLAMP's works. (I've read "Chobits" and I'm reading "XXXHolic." [Edit: I finished "XXXHolic."]) Now, do I recommend this? HELL YEAH!