Well, to be honest, Billy Bat would probably be better if Urasawa worked alone, without Nagasaki Takashi. MONSTER was great, 20th/21st CB was great, and PLUTO was a masterpiece (OK, he "collaborated" with Tezuka with that). BB is a good series, I read about ~60 chapters but then I somehow felt that the story is getting a bit too hard to follow. It's like UraNaga doesn't even know themselves how they should continue it. Anyways, BB is over 90 chapters now and I will give it an another read after the series ends. Before that it is kinda hard to read with all those breaks.
I'll be getting a big package tomorrow with the rest of the 20th Century Boys and 21st Century Boys (I already got 7 vols.). I'm also watching the anime of MONSTER with a friend this Saturday so I have a ton of Urasawa goodness to come.