Some of the improvements to the original games include a unified checkpointing & save game system. (This includes manual and auto-saving.) Also featured is an additional unified menu system, as well as Time Trials in all three games!
Arguably most impressive is the inclusion of a “fully-remastered game soundtrack, packed with all the didgeridoos, xylophones and thumpin’ bass lines you can handle, as well as newly recorded dialogue from some of the familiar voice actors who appear in the original Crash Bandicoot games, including Jess Harnell and Lex Lang, among others.”
It's been 20 years (two decades!) since the original Crash Bandicoot was released on the PlayStation One console (September 9, 1996). I look forward to getting my hands on this collection as soon as possible, if only for nostalgia's sake.