Just replaced my Garmin Dash Cam 55 with a NextBase 512GW.
As nice as the video quality on the Garmin was, I couldn't be dealing with it rebooting/locking up all the time so returned it to Amazon. The extra features such as speed camera, lane departure and collision warnings all sounded very nice on the spec sheet and to be fair worked well, but ultimately were just gimmicks and meant you couldn't drive 2 minutes without it beeping at you for some reason or other.
Got to say the build quality and form factor on the Garmin was in another league to the Nextbase, but we'll see how things go. I bought the NextBase hardwire kit to enable Parking mode and this was very easy to install; looks like this works differently on the NextBase though, which shuts the unit down after 5 mins of inactivity and only activates parking mode when the G-sensor detects movement. The Garmin would record clips whenever it sensed movement via the camera, which made it a good security camera but I never considered just how often movement happens in front of a car; every little thing was triggering it to record, including the reflection of the blue LEDs on the dash which flash while the car is on charge; had to stick the user manual over the top of them in the end to stop the memory card filling up with useless video!
Initial thoughts on video quality are that it's not as sharp as the Garmin, and it seems to be struggling a bit with exposure on a bright day, but I'll have a play around as I've seen some suggestions that I need to lower the camera angle slightly to include more dash in the shot; at the moment you can just see the base of the windscreen.