Looking at it I can't say it would be as efficient as renting a log splitter. Look at the wood they are splitting in the picture. It is perfect--no branches, it is dry, and straight grained. Not sure it would work with most types of wood.
Home Depot/Lowes sometimes have them available for rental.
When I was younger my stepbrother and I were the log splitters in our home. Once we grew up and moved out, my step dad went and bought a log splitter. Figures...