I also thought the Moto E would be better than the Lumia 630 but just watched a review and.... the moto e is so much worse. The only thing it got that is better is the RAM (and it has a light sensor?) but unlike Android, Windows Phone works preety good with 512 MB RAM. People are just pissed that they will not be able to play some games on such a low-end device.
The Moto E camera, screen and storage are just the low of lows. Camera doesn't have auto-focus, the screen has really some low quality color reproduction and the storage is too tight for anything.
The lumia 630 has an awesome larger display with clearblack for better visualization on daylight, better camera with auto-focus, double internal storage, a better cpu and a better gpu. Compared to the moto E it only lacks the light sensor and less 512MB of RAM which again is not that much of a issue on Windows phone.
So, why it was a disappointement? Because its predecessor was the 620 and in terms of hardware got a bit dumbed down. If this phone was called lumia 530, people would go crazy. But infact, this is a sucessor to the 520 pretty much and with a really big upgrade.