It's a lot more than that. Clear your monitor of grease. ;)
Outside of shine, textures will have actual depth now as opposed to feeling 2D. Things with texture will actually *feel* like the light is hitting them the right way as opposed to just having drawn-on shading.
The secondary obj is what opens the doors to the hangar. The advantage of completing obj is more of a positional one. I did have a few ideas for ways to make the secondary OBJ matter a bit more (like something slowing down the team which lost the secondary in some way or form), but that concept...
sup!
There are a few active communites who MBII quite regularly. I'd check out the Sandbox discord for starters, you can find discord channels by going here.
Kind of a biased list from the start considering how many maps are missing (Snow Facility is A tier, dust2 for me would be B, Pool Party S).
I'm gonna rank things based on overall fun, which is obviously very relative. Some maps may be more balanced, but less fun (or visa versa). Just gonna go...