Actually additional buffeting at high altitude due to compressibility effects often helps to identify a stall earlier, making it generally "easier" to handle.
OTOH, a natural pitch-down that may be present at low altitude, is usually absent at high altitude.
Also the stall itself (maximum lift, loss of controllability) occurs "earlier", at a lower angle of attack than at low altitude.
Due to the low air density, to gain a certain increment in terms of CAS/EAS in the recovery, requires a longer time of acceleration in terms of TAS, and consequently greater height loss.