I've had this printer for about 3 or 4 years now and it has served me well. It has a decent build size, heated glass bed, good looks and easily serviceable parts. Customer service has always bent over backwards for me and though I've had problems with it I would say they were reasonable problems for a printer in this price range. Also there are some simple upgrades and additions I would recommend (See below). It has simple parts inside including an arduino mega, a shield for controlling the stepper motors and heating elements and a power supply. It is not enclosed so technically it could do better with controlling the temps but I find it works just fine. I use matter control for the software.
First, the bottom of the printer is closed. This limits airflow and contributed to my arduino shield overheating and melting/burning the connections. When I replaced the shield the new ones came with a better design for the connectors that is less likely to fail, however I removed the bottom cover all together, printed stands to raise the printer off the table a few centimeters and printed a holder to hold the cooling fan directly on on the shield itself. All these upgrades are available on thingiverse if you just search for for the robo r1. I also used more metal tape on the cork insulation on the bottom of the heated bed to help hold the thermistor and heating element up because it was having a hard time keeping a consistent temperature. The support guy at Robo 3D sent me out the replacement shield and parts for free even though I was a bit outside my warranty.
My arduino mega board went bad about a year ago and had to replace it which cost me about $50 from Robo3D. My printer was an older design which used a rubber boot/cover to hold the thermister on the extruder block. The boot dry rotted recently and I had to fix it by using high temp silicone adhesive designed for chimney chutes to hold the thermister in place. Newer printers come with an upgraded hot end which uses a set screw to hold everything in place and I could buy a newer hot end to replace mine, but my fix works pretty good for right now and cost me five bucks.
I've easily printed over 10kg of filament over the last 3 or 4 years and have never cleaned or cared for the print nozzle. Recently my nozzle became clogged pretty good. Replacing the nozzle, however, cost me five bucks since it uses standard nozzles and it was not hard to get back up and running.
All in all, this is a solid printer for the $500 range. If you're okay with replacing some things here and there over time this printer will compete with a lot of other printers in the $1000 range no problem.