The Fourth Company Librarium has run an article on the Blood Angels Codex needs here.
4th Company splits the issues into datasheets vs. detachments/formations.
Blood Angels have gone through a very difficult time similar to Dark Angels where everyone gets your items and others have some things point reduced in comparison. 4th Company lists issues with Terminators, Vanguard, Scouts, Dreadnoughts and Tank squadron issues. I would also tack on that bizarre situation where we cannot take the Land Speeder Storm and Stormtalon Gunship.
There is also the issue of Devastators not being able to use grav-cannons and Assault squads Eviscerators. I have written to GW about this with no response, unfortunately.
4th Company also has concerns about anti-air, I would tend to agree about getting access to Hunters, Stalkers plus the aforementioned Stormtalon. I would have to disagree about giving the Baal Predator Skyfire as it doesn't make much sense based on the weaponry that is more short ranged against infantry.
I understand that there needs to be some distinctiveness between the codices. I like how the Dreadnoughts are different or no access to certain items but not at the cost of leaving massive weaknesses or just not being able to use all of the weapons in basic kits like Devastators or Assault squads. Further, why are Blood Angel Tactical marines allowed to use a heavy flamer but not Space Marines (especially Salamanders)? It makes no sense other than that the Blood Angels Tactical squad comes with a heavy flamer in the box because the sculptors decided to do it.
These are pretty simple and basic things that should never have happened in the first place to the BA codex. Why did GW need to rankle the BA players by actively annoying/ignoring them.
Detachments and Formations
4th Company is looking to bring the BA up to date with the Space Marine Gladius or the Armoured Task Force for example. Additionally, they look to build off of the existing formations to make them viable.