Yes the Kleiber are worth getting. Also fun is the 5th and 7th by Benjamin Zander and the Philharmonia Orchestra that has a companion CD lecture by Zander of both symphonies. (Ben Zander also praises Kleiber in his lecture).
I've heard all the complete sets, and my favorite Beethoven symphony complete cycle is a rare unheard one to most. It is with the City of Birmingham Orchestra conducted by Walter Weller; on the Chandos label. It even has the first movement of what historians think is a draft of the 10th symphony.