购物 is slightly formal. In casual speech, 逛街 (guàngjiē, to stroll the streets) is more common for 'going shopping'. 购物 is the standard term for 'shopping' on signs and in compound words.
culture
双十一 (Shuāng Shíyī, Double 11 / Singles' Day on Nov 11) is China's biggest 购物 festival, far surpassing Black Friday in sales volume. It was created by Alibaba in 2009.
