The Garmin DriveAssist 51 (like its predecessor the DA 50 - which I also own and have reviewed) is a solid piece of technology that functions as a combination GPS, dash camera and a driver assistance (ADAS) system. That said, it does have a few important limitations that you should be aware of.Here's a summary of the positives and negatives pertaining to this device; as well as a comparison to the DriveAssist 50:Positives:1) Price and value: I paid $139 for a refurbished unit, and at this price, I think it's a fantastic value. Although, at the original $299 asking price, I probably would have hesitated.2) The unit is well made, and simple to set up.3) The GPS provides clear, simple voice directions, the screen is bright and easy to follow (though of very low resolution for 2018).4) The dashcam video is generally pretty good quality; although it gets somewhat marginal at night because of the small size of the lens.5) The ADAS features really do work: the forward collision, lane departure warning and moving traffic warnings function as described. The unit also warns you of speed limit changes, red light cameras and when you are driving the wrong way (though see below on the last point).6) You can operate the unit by voice command in addition to pressing options on the screen.7) It will easily pair itself with your Bluetooth capable smartphone and give you hands free calling capability, if that's something you're looking for.8) It will also download real time traffic alerts from your smartphone when necessary. This is actually very important because Garmin's over the air network of traffic antennas is not NEARLY as good as you'd expect it to be.Negatives:1) The GPS sometimes makes mistakes and is missing some locations. For instance, it advises you to take a completely unnecessary, and slow, detour down a tiny side street in downtown Savannah, GA.2) The unit takes quite awhile to calculate routes.3) The battery life is really short (less than 30 minutes): this unit is only designed to function plugged into your car.4) By default, it won't advise you to make U turns (even if they're perfectly legal) but will instead take you on much longer ""work around"" routes. This can, however, be changed within the options. Once you make a U turn it sometimes gets confused and warns you that you're going the wrong way, even though you're not.5) The ADAS system gives false positives sometimes, especially if the sensitivity is set to ""high"".6) At night time, and in the rain, the ADAS system really doesn't work reliably (even though this is arguably, when you might need it most).7) The supplied suction cup mount really doesn't hold very well.Comparison to the DriveAssist 50:1) Although the DA 50 is supposed to be Bluetooth compatible it will NOT pair with my Samsung Galaxy smartphone. The DA 51 has no problem.2) The DA 50 can only download live traffic information via antenna (which is part of the power cord); this unit can also do that OR snag it from your smartphone once it's paired. This is a BIG DEAL. Many large cities in the South (Atlanta, Savannah, Charleston, SC) do NOT have Garmin traffic antennas meaning with the DA 50 you will never get traffic info there.All-in-all, I recommend this unit.Based on my readings of other reviews, most ADAS systems in stand alone dashcams are completely useless, whereas while this system makes the occasional mistake, but it actually does work (in some ways it works BETTER than the system in my $60K BMW that system warns SO late that metal is already crumpling by the time the alarms go off! I'm exaggerating, but only slightly). The GPS works fine, but honestly, no better than the free Google Maps app on my smart phone. The dash camera records in full HD quality, and during the day the video looks fine, but because the lens and sensor are so small, in marginal light it looks worse than the video from some $50 stand alone dashcam units.My overall conclusion is similar to the one I drew for the DA 50: If you ONLY need a dashcam or you ONLY want a GPS, you probably shouldn't buy the Garmin DriveAssist; however, if you want both of these functions in one machine, and you're curious about ""smart"" driver assistance / collision avoidance systems, and you want to test one out for very little money, I think you'll be happy with your purchase. Overall, I do recommend the DA 51.