A little over a month ago I subscribed to the dollar shave club using their most common option which is a cartridge with four blades. It costs $6 per shipment (they typically ship on a monthly cycle) and you get four cartridges per shipment.
I now know why they send you four per shipment - they aren't very sharp and they dull really quickly. I could get, at most, 2-3 decent shaves with one cartridge and I typically use a Mach III Turbo for about a month (10+ shaves) before I notice any dulling. However, the quality of the blade wasn't my only problem.
The cartridge on the four blade is just too damn big for me to get a good shave around my nose and mouth. The bezel gets in the way and prevents my getting within the last couple millimeters of my nose so I end up having to use one of my older Mach III Turbo's to finish the job. Really, the only thing the dollar shave club has going for it is the price - but the blade is worthless to me if I can't actually shave my entire face.
Thus I've switched to a different subscription plan that will give me exactly the cartridge I like on the schedule I like. Amazon.com offers a subscription on all sorts of products and I've setup a recurring subscription for Mach III turbo cartridges every five months. I'm actually getting 10 sent every five months as I hope to shave my head a little more regularly. You can order them without a subscription or customize the frequency from 1-6 months.
With the dollar shave club I would have spent $30 for five months of cartridges and with the Amazon option I'm spending $28.97. Sure I'm getting half as many cartridges but they last twice as long and they do a better job of shaving even when dull than the dollar shave club blade did while sharp.