The instantaneous 'snap' from the snares and hi-hats when they're struck will have gone because the samples are all stretched out due to pitching down. Layering other snare/hihat sounds can add more snap to them. But can be hard to achieve.
Also Adjust the decay of the hits, this gets rid of the unrealistic 'pitched down' noises after the main strike of the instrument. You want a bit of release so it doesnt cut off straight away though.
Boost the higher frequencies slightly, and lower low frequencies.