The differences from the 3520er:
* Only 1 alarm set (instead of 2)
* 3 alarm tones (instead of 5) - including 2x birdsong, 1x piano music
* Matt plastic housing as opposed to clear housing when 3520er, thereby acting somewhat inferior
* Lack of red tone
* Lack of adjustment of the "Sunrise length" - this is fixed with 30 minutes of
Since I had set minutes Sunrise at 3520er 20, this change is the one to which I myself have yet to get used - the lack of flexibility in the setting leads to a star deduction. Otherwise, the missing features the additional cost of 45 euros was not worth it to me. The basic task of awakening with light, the device meets very well, also the sleep convinced me.
Negative point here as well:
* Very significant time LED even at the lowest level in the dark - that bothers some falling asleep ...
Conclusion: a good device with improvement in the individual settings. Given even this "little brother" of the price you might expect more here.