Ah, Debussy!
Gieseking was long regarded as the ultimate Debussy interpreter. And he does have some wonderful pedal effects and tonal colouring. But I find he lacks something of the capriciousness and humour in Debussy, which is also very important. Try Cortot's recording of the preludes, they are completely opposite and very interesting (allthough I don't agree with them either).
The recording with Debussy himself playing I have, and it is also very interesting. He does some things which no modern pianist would dare to do with Debussy. But Debussy was of course not first and foremost a pianist. Besides it is piano roll recordings, and cannot be completely trusted.