We really liked the orignal Yocan ExGo, and the ExGo II ups the ante in some small, but meaningful ways.
Here are the main improvements, what's the same, and what's different:
The heating chamber now features two heating coils inside. This creates more heat more quickly, letting you vaporize more wax concentrates at once without overwhelming the coils. However, it seems as though the base on the ExGo II will only work with the newly designed heads and are not compatible with the original ExGo coils. In an interesting twist, the ExGo II coils WILL work on the older model. So the ExGo two works on both base types, but the original only works on the original.
Also, it's tough to say, but the heating chamber looks a tiny, tiny bit larger on the ExGo II, but not by much--probably just enough to accommodate the extra heating coil.
There's now a removable cap over the heating chamber to help keep things clean and contained. It's optional, but it helps.
As before, the mouthpiece is still adjustable. You can screw the mouthpiece in two different places to change the height of the mouthpiece. The utility of this is still sort of lost on me.
This marks a big difference between the original and the new ExGo. The original clocked in at about 2.6 to 2.7 ohms, meaning when you cranked the voltage up to 6V, the coil was intensely hot. However, because the ExGo II now features a dual coil design, the resistance is down to 1.3 to 1.4 ohms, so 6V on a variable voltage device won't net you the same amount of heat. Instead, that intensity is divided a bit between the two coils. So you're probably getting the same overall heat, but just distributed throughout the chamber instead of concentrated in one spot.
Also, perhaps a rare scenario, but if you're using an ExGo II atomizer head in the base of an original, it probably won't work right with a variable volt battery. Not sure how many people will find themselves in this odd scenario, but just a heads up!
Just like the orignal, this new model features an airtight chamber. This creates an interesting effect where you can vaporize your wax, but wait before you inhale. It will stay trapped inside the glass chamber (presumably for you to observe it in awe). Kinda neat.
Finally, you get the same accessories as before. Two total atomizers, one packing tool, a beauty ring to fit smaller batteries more aesthetically, and a product authenticity code (not an accessory... but there's nowhere else to mention it in the review that feels natural).
So those are the key differences. I would say if you already own an ExGo, the second model isn't so far advanced that it would replace your original. However, if you aren't on the ExGo bandwagon, yet and are thinking of grabbing one, I'd say the ExGo II is a fine place to start. The only real caveat is what seems to be a bit less overall heat when using a variable volt battery, but the plus of having two coils take on your concentrates might outweigh that.