Biggest complain is the loot and gun variety. We are a generation behind even the first Borderlands of gun variety and variations. All guns look the same... There isn't much that separate a lvl 1 scout than a lvl 15 scout rifle visually. And it's shame. In borderlands, there are different gun manufacturers and each gun you loot will be a base from that maker giving him it's look and it's base stats. Then, the gun randomisation will add a different grip, sight, stock, barrel of different maker (different design) and tweak both it's stats both visual. I never felt like having twice the same guns in Borderlands.
In Destiny It's a grey assault rifle, now it's a Shingen AR, it's blue. Now it's a Cydonia, it's blue, with a aim point. Yoohoo... Boring. What is a legendary gun if it look just like any other one ? Hope the legendary / exotic stuff are really different designs and not just paint jobs.
Then, no maps. Game based on open world exploration but no map. Okay... To get a map, go out your level, have a + 1 minute loading to go to orbit, check the map, go down back to your level with another 1+ minute loading. Seriously, what is the point of orbit ? Couldn't we just had the Map anytime and skip the entire orbit part that is just USELESS time wasted loading twice longer than we should ?