Marginal costing has several advantages and disadvantages according to the document. The key advantages are that it allows for better cost control by avoiding arbitrary allocation of fixed overhead, is simpler to understand than other costing methods, eliminates varying unit charges, helps with short-term profit planning using break-even analysis, and prevents illogical carry forwards in stock valuation. However, the document also notes some disadvantages, including that segregating all costs into fixed and variable may sometimes give misleading results, ignoring fixed costs in closing stock valuation gives a distorted picture of profits, it does not consider semi-variable costs, and there can be issues with under or over-recovery of overhead estimates.