The economic calculation problem is not the bugbear it is made out to be, and quite frankly capitalism suffers from the mispricing of assets, which is evident by the repeated bubble economies which keep devastating it.
Socialist economies still use the pricing mechanism in order to allocate resources and provide information about cost, but cost is based on the amount of resources used to produce the product - the drain on the economic resources of the entire community. Cost would factor in the general importance of the commodity and the quantity available. All factors of production have factor-valuation tables calculating their respective prices based on the above criteria. While it is true that precise calculations would be difficult to implement correctly without feedback, planners are quickly availed of feedback and make adjustments to price accordingly if the prices of a particular commodity were set too high or too low and cause surpluses or shortages in supply. For example, the much maligned "food lines" in the USSR were due to a larger disposable income by consumers and thus a larger demand for high-end food products like meat than ever before. The state had set the price too low for these goods, but ironically had they set the price higher citizens would eating less well than they were because they would have less disposable income. As data tables clearly show, Soviet diet in terms of caloric intake was on par with or greater than most western countries. At any rate, the minor inconvenience of food lines is better than the total misallocation of resources under capitalism, in which widespread hunger coexists with large-scale food waste.
Socialist pricing in theory is more efficient because pricing in a private initiative economy relies on arbitrage to correct mispricings, which is entirely voluntary and based on whether or not the correct incentives for arbitrage actually exist in a particular market. Where arbitrage falls apart, serious problems occur which cannot be readily corrected.