On a mechanical keyboard (mine has Cherry MX Browns), the point at which the switches close is before the key bottoms out. Depending on the switch type, the closing point can be felt, too. They're also driven back by mechanical springs, rather than a rubber membrane. So, rather than mash the keys until they stop to guarantee a letter press, the typing feel is lighter and more controlled. It's also much bouncier, thanks to the springs - like bouncing on a trampoline, rather than trying to jump on a hard floor.

I went from old-school gummy keyboards (Yay ancient Dell hardware) to laptop-style scissors keyboards, and when my last one died, I splurged and got a mechanical keyboard instead. It's similar to a laptop-style keyboard feel, where there is a very definite point of engagement rather than tons of mush. However, the throw is still long, and the bounce-back is a new experience.

It's all about feel - definitely look around and see if you can borrow one (or multiple - there are a half-dozen different flavors of mechanical switch from Cherry alone) to try before spending the not-insignificant amount of money to buy one.