Amazing quality, and a top notch soldering job. I've built a v5, but they make this look easy-- and extremely professional.
I bought the Art Version, and photos don't do the product justice. The acrylic top panel has been printed on both sides. This gives the logo in the bottom right corner a bit of a 3D effect. Further, the red lines on the PCB match the green lines on the acrylic. So that too has a neat appearance to it.
As for functionality goes, I think v3 ALTER is a very convenient size. It has slots for SNES (SFC), Genesis (MegaDrive), N64 and GameBoy (Color & Advance). This is plenty, and more are supported with adapters if needed.
I noticed a review where someone said the SD card is a pain to get out. I didn't have the same experience. The model I have features a microSD slot, and this is spring loaded. To remove, just push the microSD further in, and it will eject for you.
Great product, and awesome customer service. Very happy with the quality.