All of the Aspects of the Game

PVE

Destiny’s PVE is split to 5 parts: a story campaign, 3 man strikes, four 6 man raids, 3 man round based horde mode called “Prison of Elders” (abbreviated as poe), and patrols around 6 different areas. Vanila Destiny’s (the original) campaign is considered by the community as a low point for story telling through the game’s history. Featuring a confusing campaign most of which remains unexplained to this day and the main way to experience it is through the Bungie website in grimoire cards which are also collectibles in the game. The best content of the game is considered as the raids and back then especially. Vault of Glass was the first raid and the main redeeming factor of the vanilla game.

PVP

In the launch of vanilla pvp was widely unbalanced with very few weapons considered usable. This was the auto rifle meta with the exotic suros regime taking center stage. Later on the auto rifle weapon type was nerfed in general not gaining the same grounds as it had back then. After that the handcannon meta took over and the exotic hand cannons took center stage. Guns like the Thorn, Last Word and the PlayStation exclusive Hawkmoon. This meta was considered unfair and broken by many standards with time to kills dropping as low as 0.63 seconds.

The Dark Below

In terms of pvp maintained the same meta with little changes to the overall feel. Considered by the community as the worst expansion to the game with very few changes, a short story, disappointing strike and a decent yet broken raid.

The House of Wolves

Introducing the first decent story in the destiny universe with a makeshift fix to the leveling system and a disappointing end game. POE wasn't a raid but it was better than a strike. It continued on with the pvp meta and reached the most broken ever.

The Taken King

TTK changed everything introducing a complete gear reset a raid which was comparable to a MMO raid. Year 2 was also the first year to introduce seasonal events rather than dlc. This was later discovered to probably be a bad move on the developer's side with multiple dry periods that caused a lot of players to drop the game. On the other hand this was probably pvp at its best with a very balanced setup most guns could work in this meta with pulse rifles thriving.

The Rise of Iron

Rise of Iron was the final expansion for Destiny 1 and came a year after TTK. While not being on the same scale and level of the previous DLC. ROI introduced a new less mechanical raid. The raid was fast paced and looked very interesting. But this expansion had the most boring and unfun meta throughout all of D1 with the removal of secondary ammunition from spawn which lead to an unbalanced meta with only guns which were able to regenerate ammo to be viable secondary choices.