I much prefer the ones other motor manufacturers do which are hid behind the handlebar.
Edit: that said, it has a much higher quality feel than the unit supplied with the missus' Yamaha pwse, but then I think the Bosch motor is more expensive.
The purion one sits in a place too prone to damage on a MTB, in my opinion.
Other that that I'm quite happy with the bosch system. I've learned to deal with the motor lag.
Puron. Have no problems with it. My last bike was Shimano. The display is very cool and the position is perfect in my opinion. BUT much too bright when riding at night .. even at its lowest setting. Also way too complicated to change settings on the Shimano.
I had an Intuvia originally, but one too many OTBs trashed it so I procured a previously cherished Purion. I miss the effort bar and I'd like a more accurate battery level, but the Nyon and Kiox are for too expensive and far too exposed to risk it.
Purion =) mostly because I want to ride and not look at the display all day.
however the new phone option from Bosch seems interesting for longer rides