Adventures in 'Pataphysics is an excellent volume containing a focused (and nicely translated) selection of Jarry's work, and is complete with illustrations from the originals and extensive notes in the back of the book.
The first work in this volume is "Black Minutes Of Memorial Sand" -- one of Jarry's earliest works; a novel written in a hodgepodge of styles (poem, play, etc.). The second piece is "Caesar-Antichrist" -- a play (the first act of which actually appears at the end of "Black Minutes"). While these works may not be the easiest to follow, that is probably not so much the point with much of Jarry's symbolist and proto-surrealist work. Certain elements and characters pop up throughout these and his other works, notably the Ubu family.
Next we have a section containing four essays, including the amusing mock-scientific "How To Construct A Time Machine". And finally there is a selection of many short (1-2 page) pieces that appeared in journals and such of the time. A handful are quite dated, but for the most part they are a great read -- Jarry has a great gift for satire.
It is difficult to sum up what it is like reading one of Jarry's works. From bizarre symbols and wacky metaphors, to hilarious episodes and confusing allegories, Jarry takes the reader on quite a ride. One might compare it to Lewis Carrol or Monty Python, but for the more mature and less sane reader.
This is a perfect introduction to Jarry's work for the adventurous reader. And for those already familiar with Jarry, this is an excellent volume you need in your library.