Since this technology uses cable rather than your telephone line, you don't tie up your telephone while you're surfing and can continue to make telephone calls as usual. Also, using your cable modem doesn't interfere with your cable television reception. You can share your modem among several computers by connecting them together in a network. You'll have to buy special hardware device and software to set up this network. Once connected you can also share files and printers between various computers.
Modems are notorious for breaking down without warning.
You should only buy well known brand from a reputable company that offers a rock-solid warranty.