Overall This is a great PV. There are over 10 designs to choose from, battery life is great, and you get lots of vapor! Note: The youtube vid attached is not mine, but the review of GrimmGreen himself. He tends to give very reliable videos so that's why I used it.

This is the only high voltage mod I have so I have nothing to compare it to. As of right now, I don't feel I have to compare it to anything because the Xhaler will be my last mod. That's how much I like it.
This thing is built like a tank but yet it's not as heavy as it looks. Most likely due to the aluminum body. I'm not going to go into everything that came with it. you can find all the available options on the NHaler web site.
So I plug in the 2 RCR123A 3V batteries, screw on a 901 atomizer, press the button and POOF!, there goes the atty. I thought it may have been a bad atty but my dumb a$$ did it again. First lesson, make sure the atty is WET!. And I mean Wet! Once that valuable lesson sunk in, I had no further atty problems.
A well primed atty with High Voltage Kent and I was ready to start by new vaping experience. A few primer puffs and then a nice long draw. Dayum!!, I though I was going to cough up a lung. This thing is one powerful fog machine. The High Voltage Kent delivers a great throat hit on a 510 but I did not imagine how much it would be amplified by the Xhaler. (remember, this is my first experience with a HV mod.) I have found vaping nervana!
Let's try the other flavors!! I spent the afternoon trying almost everything in my inventory. The Xhaler came shining through with everything from the standard juices, lung juices and especially the HV juices. Incredible vapor production all around. The higher voltage seems to enhance the flavorings of everything I tried. I find the HV juice is the absolute best regardless of the flavor. Drew did his homework when he formulated HV. It does exactly what is it supposed to do.
The Xhaler itself........................
The unit is a bit over 3/4" wide and approximately 4" long (without the atomizer). The atomizer cap itself is made out of brass. The color of the brass compliments the colors of the Xhaler but it does have a tendancy to tarnish. I'm sure if you used a good polish/protectant, you could retard the tarnishing a bit. The bottom end cap is made from Delrin (according to Drew) and acts a voltage resistor when power is applied. When the bottom cap is screwed in tight, it somehow makes contact with the button mechanism and reduces the voltage somewhere around 1V. When the cap is unscrewed or loosened, that contact is removed and the full power of the batteries is realized. I am no elecronics whiz so I cannot tell you if, how or why this works. The entire unit is fully mechanical with no wires, pc boards or soldered connections. I have experienced the button not making perfect contact a few times but that is easily remedied. Remove the end cap and swab the contacts with a q-Tip and a bit of PGA or use the old sandpaper trick to clean the connections.
I give the Xhaler a 10 out of 10 for performance. Another 10 for the WOW factor. If you don't have one yet, you should seruiously consider getting one.