I felt the same about my Lumia 630. I broke the screen and ended up switching to some HTC abomination because I needed Android, but the 640 was cheap, smooth, fast, well ahead of its time in mobile UI and it was actually pleasant to use.

I can't believe how badly MS have handled Windows Phone. Splitting the market between WP 7/8/10 was insane given how small a user base they had.