ProVaris are almost just as expensive as Darwins. And he wasn't asking about a Provari, he was asking about a Darwin. "Get a Provari" isn't a very helpful answer.
Plus, "toot". Shudders.
Anyway, to answer the OP's question, yes, I have handled a Darwin quite a bit. One of my co-workers spent almost $250 dollars to get his. The LCD display was awesome, but two things bothered me: the 510 connector moves up and down, and it just looks so easily breakable. It also is a goofy feature, too, btw. What's the point of having the 510 connector move around? The other thing that bothered me was the size and shape of it. A very bizarre looking mod, to say the least.
The Darwin helped pioneer variable wattage, which seems to be the way a lot of high-end mods are going (or at least including). You can get variable wattage, the same main feature of the Darwin, for under 50 bucks (look up the Vamo, that thing is amazing for the price). Also check out the Zmax. The Zmax is a little more expensive, but honestly, I think a Vamo is a better device.
Also, ProVaris, while amazingly sturdy and well-crafted pieces of American machinery, only provide variable voltage. With variable voltage, if you change out cartos or attys or clearos with different Ohms, you have to readjust the voltage (dialing it up or down to handle the Ohm resistance). With variable wattage, you can set your PV to any specific setting (say you like your vapes at 7 watts, that is your sweet spot; you decide to switch out a 2.0 ohm carto for a 1.5 ohm carto. Instead of dialing the voltage up or down, the variable wattage setting remembers what your sweet spot is and automatically causes the PV to fire at the exact voltage each and every time.