Charging an iPhone 4S with a Samsung USB charger
While I personally wouldn't attach a non A-branded charger to my iPhone, theoretically if the charger delivers 5V and does it on a USB connector, it really doesn't matter from where the power comes.

The more amps the faster your iPhone will charge.  I've been charging my iPhone with my iPad charger for years without any problems.

Currently Apple has 3 types of USB chargers


iPhone charger: 5 volts 1 amp = 5 watt
iPad 'old' type: 5 volts 2 amp = 10 watt
iPad 'new' type (from iPad 4 on): 5 volts 2.4 amp = 12 watt


The Samsung 1 amp charger you're talking about will give you the same results as the original iPhone charger.