Apache 1 vs Apace 2

I know that Mac OS X Server 10.2 comes with Apache 1.3.x turned on and Apache 2.x off but installed and apparently Apple is going to release an update to 2.x today with some other server patches. Is there any reason I should be using 2? What are its main improvements? Why does Apple have it disabled? Does it break anything important that I might be using? Thanks!