If you need to zoom in close and have pictures like shoulders & above type facial shots, then you would need 6x-12x zoom, depending on how far you're from your subject.
Whether you'll experience blur due to camera shake will depend on the light condition (which will determine your minimum shutter speed) and focal length used.
Here are samples of what I shot at 8x zoom (72mm focal length = 280mm equivalent on 35mm format) with my Coolpix 5700 when I was within 1 metre from the stage and within 3 metres from the subject and the indoor light was pretty ok at Raffles City :
F/4.2, 1/60 shutter speed, ISO 200 (ISO 400 was too noisy).
If you're further than this kind of distance, then there may not be enough light and the shutter speed may become too slow 1/8-1/30 and you will have problems with blur images at 10x zoom on S4.
So you really have to know the light condition first.