The amount and toughness of enemies scales way too far when grouping. I can solo fine, but when I group with one friend and we do the same mission together we get ripped apart every single fight. Two Mirandas vs two Neg'Vars? WTF? I died 3 times, partner once cause he ran away better than me
This was not an issue during closed beta, so whatever you changed to make grouping far harder and slower than individual combat needs to be reverted, or there is no point to grouping.