Here is a comparison of three worlds all generated using the same seed (-123775873255737467), centered around spawn:
Default 1.7.x cave generation for comparison purposes:
No caves; ravines, mineshafts, and lakes still generate; it is also important to note that dungeons are extremely rare without caves, although the loot can be found in chests elsewhere (music discs from creepers, dungeons also have only two out of 12):
Old cave generation; generates the same way as versions through 1.6.4, including across old-new chunks (no cut-off caves):
Double old cave generation; twice as many caves as old cave generation: