According to Wikipedia "The Gillette Mach3 is a line of safety razors produced by Gillette and introduced in 1998 after more than $750 million in research and development costs. The three blade design is marketed by Gillette as allowing for a shave with less pressure to the skin and with fewer strokes, thereby reducing skin irritation.”
A long time ago as a young lad, I started off using Bic disposable razors, with one blade that nicked a lot, then went up to something with two blades that nicked a bit less, and then to something with four that clogged up all the time and still nicked. It seems pretty obvious that three is about the right number of blades for most people. The handle is a little lightweight compared to some, but perfectly functional. Fitting a replacement cartridge is fiddly, but once in the blade is snug and secure. The cartridge has an open back, so it will not clog up with shavings, and should last for ages. When shaving it has a nice feel, dragging slightly as it catches the bristles. It is very unlikely to give you a nick, even when fresh out of the packet. On the downside it is not the closest shave I have ever had, I often lather up and shave a second time.
A recent blog asked readers for their favourite razor, and this was the clear winner out of the cartridge razors. Not sure how they spent $750 million on research, but the fact that something that launched in 1998 is still in production tells you that this is pretty near perfect.