They are an excellent light. A lot of the noise upon launch was by Neptune fans and people that disliked Neptune or some part of it. Others had agendas so when one looks back on the product launch from a hobbyist perspective it was a sad state of affairs. Even if one removes the bias hat.
Looking at the light please note that I run two and have for well over a year now. The display hasn't crashed. The lights have not broken. There is no sticky stuff on the surface. Honestly when I look at the light kit on its own it has held up excellent even as I have them mounted 8" above the water surface. I've splashed, fish have splashed (true, my Zosters butterfly is a odd duck), and it is fine. No salt creep. Nothing. Both fans are working great. No alerts, alarms, nothing. If I am being honest they are pretty boring from that aspect.
As far as the light output I've not noticed any drop off in PAR. I took some measurements before placing them in the display and about 2 months past. Everything is more or less the same. I should note that I do not run my kits at 100% but rather 85% at peak of the day. Ramp, ramp down, 0700 to 2100. Moon lights are at 5% I think. Oh - 2 x SKY over 210 gallon display which is mixed reef at 54 x 30 x 30.
TL; DR sale is over, price was a great price point, light is solid and held up well, hobbyist have to weave through the noise from all parties and make their decision. Ignoring that I think most owners will say the same thing. Good light, holds up well, no issues. Of course I can't speak for all but that is my experience.