I think China are being very smart with their defense expenditure. They're obviously playing the numbers game at the moment to counter the US' pivot towards them and building lots of cheaper ships with minimum, but very capable combat ability is a smart way of placing boats in the water, as soon as possible. On their own, they of course would be no match for the US fleet or even other regional naval powerhouses, like Korea and Japan, but as a swarm, which is how I would expect them to be used, they would give any opposing navy something to think about. Given how relatively cheap they are and the rate China are putting them out, these new corvettes will give China ample coverage of modern naval warships to patrol their near coasts.
China, as a nation playing catch up to other naval powers, have played it smart and not put all their eggs into the metaphorical one basket. China could have easily fallen into the trap of building massive destroyers and cruisers with equal or greater armaments, and bankrupt themselves to field enough of them to cover their vast coastline. Building smaller ships with modern capabilities like this 056 and the 054A frigates is exactly what China needs to do right now, to get their modern warship numbers up. This strategy is the most economically sensible way of modernising and strengthening China's navy, along with gradually building up their numbers of modern destroyers and eventually more aircraft carriers and even cruisers.
Here in the West, people seem to look on at China's military build up with great suspicion, but if I were in their shoes, I'd be doing the exact same thing, given the US' history of military interference around the World. Good on China for their impressive ascension both economically and militarily.