Bart and Chris are right when it comes to the real significant change comes in September.
However, there's more options for hobbyists in the May Update. From memory, if you start playing again from May 8th you'll have these changes:
- Warmind Story Missions - DLC
- New Quests - DLC & May Patch
- New Adventures - DLC
- 3 New Strikes (1 PSN exclusive within that)
- New Game Mode, Escalation Protocol (7 waves with some mechanics then a boss. 5 bosses in total, rotate weekly) - DLC
- Crucible PvP Ranking (5 levels, like OW but rewards as you progress) - May Update
- 45 Data Collections to find, likely to be linked to a Quest
- 40 Music Boxes to find, likely to be linked to a Quest
Nearly all buffed in different ways (see other threads)
- Exotic Masterworks (Mini quests per weapon that we have to figure out)
- New Raid Lair, Spire of Stars
- Vault Space increased from 200 to 300
- 4 Emote Wheel
- Delete directly from Postmaster and Vault (finally)
- Unique Nightfall Rewards - April Update
- Nightfall Challenge Card Scoring (Add modifiers, scores to reach)
- Lengendary Nightfall Challenge Card from Xur - May Update
- Heroic Strike Modifiers - May Update
- 6v6 Iron Banner - April Update
If you haven't played Osiris DLC, You'll have that as well to do which is similar to Warmind stuff minus the new game mode. Although does have 11 guns to grind.
Think thats it. Should be stuff for a few months and then the big update in September (Random rolls, Weapon Slot Changes, large DLC, Etc).
For me this is worth it to tide me over til Sept. Need to do more raids.
until