I was able to pick this grinder up used for about $25 without a battery. I figured it would make a good addition to my 18v collection. Overall I am pretty happy with the tool, it performs pretty well for what it is. This tool is not suited for longer, heavier jobs. What it is good for is being portable and a good option for quick jobs, when you don't want to carry a cord around.
Under heavy load, it can tend to bog down. This is likely a built in feature to prevent damaging the battery. If you press down too hard, the motor will shut off and you have to reset the switch. This would not happen on a more powerful corded grinder.
Another flaw for some is the toggle switch. In many cases I agree that a paddle switch is what you want on an angle grinder, however in this case I don't think it matters as I only use it with abrasive discs for stripping paint. A paddle switch is more important for heavier grinding and cutting jobs, where one might need to slow down or stop the wheel quickly.
Flaws aside, for the price I paid I am happy with this tool and I find myself picking it up instead of the corded grinder for all but the heaviest of jobs.