I've used the Mach 3 Turbo for about 6 months. Before the Mach 3, I used an expensive Norelco cordless electric razor.
The Mach 3 Turbo is a large financial decision. The disposable blade cartridges cost $1.50 - $2.00 each in packs of 4 or 8, and the razor (around $10) only comes with two of them. Blades should be changed every 3-6 shaves, depending on personal preference. By comparison, the Norelco electric was $60 and a new set of blades was $30, but they only had to be changed about every 6 months (again, depending on personal preference). Since the cost of electricity is negligible, the Mach 3 is more expensive over time than the Norelco electric, but requires a smaller initial investment.
Typical shaves with the Mach 3 are very easy and fast - almost as fast as with the electric. But I'm satisfied only with the best. Based on the recommendations of the Something Awful Forum members, I tried shaving in the shower with regular hair conditioner (VO5 Kiwi & Lime Squeeze) instead of shaving cream. It's amazing. The shaves are even faster because the conditioner softens the hair and is slick enough to double the "turbo" of the razor.
Unfortunately, the "turbo strip" is unimpressive. When the cartridge is new, it does help the razor glide more quickly over the skin, but it wears away or peels off after 1-2 shaves. It's more of a gimmick than a feature. While it lasts, it's quite nice, but if you want that nice feeling with every shave, you'll have to change the blades much more often (and therefore pay much more to shave).