OK, here is a slightly more informed view:
Game is very pretty. Graphics are mostly great, though nothing astounding if you are used to gaming on a PC. I would say they are about equal to 2013 PC gaming quality.
Shooter Gameplay mechanics - imo, this is where the game really excels. Pretty much everything about combat mechanics are exceptional. Guns/shooting feels meaty and satisfying. Controls are very smooth. The actually shooter gameplay is what this game does very well.
AI - The AI is underwhelming. Enemies don't really swarm or flank unless you are in the immediate vicinity (like almost melee range). If you stay at a moderate distance, you can pick them off with little risk. Further, the is a small variety of variance in enemy tactics. Vast majority react the same way and as you progress, it seems like they are just re-skinned and buffed.
Level/zone design - though the graphics are pretty, zones are very similar with a lot of reused assets. They become monotonous pretty quick. None of the zones are very big and even pvp maps are on the small side.
Missions - missions are completely forgettable. If doesn't take very long into the game before you forget about the story and lose track of why you are doing anything other than because its the next objective on the list. Most missions are just kill x creatures or defend x number of waves or kill boss x and spawns. Very little creativity and becomes monotonous QUICK.
Sound - Music and sound effects are generally pretty amazing imo.
Story - This is the biggest disappointment for me. Game makes little effort to flesh out a coherent story. And its short. This game is in no way story driven. You very quickly lose track of any narrative arc there might be and major questions aren't answered. Or even asked.
Dungeons / Raids - Max party size is only 4. There really is no such thing as a raid in this game. There are no real fight mechanics. Dungeons are just clearing mobs and then plinking at a boss from cover for 10 minutes until is dies.
RPG Elements - simply, they don't exist. Yes, there is random loot drops. And your character progresses, but there are no real choices and each class progresses the same from person to person. There is no exploration at all. There is no interacting with NPC's. There is no real story or choice. Even a game like Borderlands is 10x the rpg this is.
Social/mmo elements - Again, they don't exist. Its a pain to group with people and you have to pay for SEN to group. There IS NO PROXIMITY OR ZONE CHAT. FAIL FAIL FAIL. Its impossible to talk to people without grouping first. This means you could be standing right next to someone who is looking to group for the SAME MISSION and there IS NO WAY TO KNOW. There is NO WAY to meet people IN GAME. Its fucking absurd.
Travel mechanics - every time you travel between locations, you have to load to orbit, choose the next location, watch a long ass cut scene, then load to your new location. Were are talkin full load times. It takes like 5 minutes to go somewhere new. And when you consider you usually go back to the tower between each location, you are talking about a frustrating amount of waiting.
The world - its fucking tiny. The tower is a joke. Its supposed to be the main hub, and there is almost nothing there. There are a handfull of shops and a couple mission givers and THATS IT. There is NO exploration in this game. Every location you travel to is a small zone and there is no way to transition between them without going back to orbit first.
Final Thoughts - I have no idea how Destiny came to be considered a shooter / mmo / rpg hybrid. Its only one of those three things. This game is a flat out grinder FPS.
Somehow (maybe by design) Bungie allowed the public to thing this game is something that it is not at all.
Destiny is a cross between Diablo and Halo. Its a gear grind shooter. Thats all. It is not an rpg and is not in anyway a mmo.
If you want a Halo-Diablo grinder, you will love Destiny. If you are looking for anything more, save your money, you will be disappointed.