I bought the HF3520 - used, was about two years old. I used it for another year then it started to misbehave. Sometimes it wouldn‘t light up or just turn off the light again after reaching max brightness. I loved it but I wouldn‘t buy it again.

That thing isn‘t able set the time via radio. Also if you lose power, you have to set the time again. No battery support whatsoever. I expect more - this product hasn‘t really evolved over the years yet they are pricey!

Now I bought a Philips Hue bulb and a bridge so I can use it as my sunrise alarm. Works like a charm and is even more versatile.