1. The differences between Hunters and Fireflies are purely cosmetic.
2. Customization looks to be as good as UC3 in terms of options, colors not so much.
3. The average map size in TLOU's MP is bigger than UC3, coupled with the slightly smaller 4v4 format it should result in a more open/tactical feel to combat rather than a cluster@$%! like many of UC3's maps.
I for one applaud this design decision. Plus it melds with the whole philosophy behind TLOU's gameplay and universe.