I have been using this for over a month now on various trips, and it works as advertised. Resistance levels are solid, adjustment is easy either manually on the unit or through a mobile device. The different resistance settings (eccentric, concentric, normal) are interesting to play around with and add some nice variability to my workouts. Great value for the price (in terms of functionality, portability, & accessories). The units hold a sufficient charge for my standard hour-ish long workout. I wish it had higher resistance levels, but 67lbs in a single compact and light weight unit is pretty impressive... and honestly sufficient for most exercises.
I bought the dual pack, so using 2 units together helps a lot for when extra resistance is needed. That said, for me this is primarily a travel accessory. I don't view it as a home gym replacement since it can't produce enough resistance for squat or bench press (for me), but I could see this being a good home gym system for beginners or people who aren't lifting super heavy. I understand the motor and battery tech for 500lbs of resistance in a unit this small just isn't there yet. When it is, this thing could feasibly replace a home gym for even advanced lifters.
Overall, I am glad I bought this device and look forward to seeing how many years of use I can get out of it!