I finished it yesterday and loved it all the way through. A sequel or DLC please!
I actually agree with the complaints of the side missions becoming a bit repetitive and filler by the end, there's perhaps a few too many and they break up the story progression too much. I enjoyed the gameplay so much that I didn't mind doing them, but I wish they had more 'story' other than the little flavour text you get on the mission start screen.
The customisation is great both in terms of character skills and cosmetics, although inventory management became a bit of a Mass Effect nghtmare by the end. Juggling gear between characters but locked behind those returning from side missions seemed a bit unecessary.
The new XCOM solved a similar problem in Chimera Squad of creeping in to missions for too long with the breach mechanic, this doesn't make you move too far without an encounter, which is really nice.