Most of their novels are good read. Especially "Hard to Be a God", "Snail on the Slope", "The Ugly Swans", "The Inhabited Island", and, of course, "The Roadside Picnic".

http://en.wikipedia.org/wiki/Arkady_and_Boris_Strugatsky

Actually, it was very interesting phenomena, how in age of strict Soviet censure these seemingly Sci Fi books were filled with philosophical, humanitarian and political ideas. Lots of Soviet people grew up on these texts, within these imaginary worlds, which are so much better than harsh Soviet reality.

Nowadays, btw, authors of the next generation implant big ideas into what seems to be stories about vampires.)