While thinking about what else to write, I realized that I hadn't reviewed all of the special units from Deathstorm. While they're not super different from the basic units, they do have some specific uses. I already reviewed Captain Karlaen, but here are the rest of the units.
This squad is five standard Terminators, upgraded to have a heavy flamer and chainfist. This is not a build that you'll see often, and the squad is not particularly useful on the table. However, Sgt. Alphaeus has Preferred Enemy (Tyranids), which makes the squad a lot of fun in a narrative game against Tyranids.
Raphen's Death Company
This is a squad of five Death Company with jump packs, armed with a thunder hammer, power fist, power sword, and inferno pistol. Obviously, this is a lot of upgrades on five models, and the squad is quite expensive. They do have one massive advantage: they're Troops. Raphen's Death Company are the only jump unit available as Blood Angels Troops, and they're a decent choice for your compulsory Troops if you want to run an very assault oriented list. I still think some Tactical marines are worth it, but this squad would be fun to play in a very assault oriented list.
Cassor the Damned
Cassor is a Death Company Dreadnought with blood talons and a magna-grapple. He doesn't have any special rules, but he is a Troops choice as well. He's quite slow since he can't take a Drop Pod, but you can fix that by either taking a Fast Attack Drop Pod or putting him on a Stormraven. Again, taking Cassor will make your army smaller by cutting out your more numerous Troops choices, but he would be fun to run in a super assaulty list.
Strike Force Deathstorm
Fielding all of these units in combination qualifies as Deathstorm, which gains two special rules. Against all Odds makes Karlaen and Squad Alphaeus Fearless and gives Raphen's Death Company Counter-attack. In addition, Karlaen can call a Bloody Toll, which allows all of the units in the Formation to re-roll failed to wound rolls for a single Assault phase.
Taken together, these are good rules for the units involved. They're all pretty assault oriented (even the Terminators, due to the heavy flamer). Again, this Formation would be kind of fun to play in a narrative game, and I'm looking forward to getting mine painted up and playing through the Deathstorm campaign.
In conclusion, Karlaen and Raphen's Death Company add a bit of flexibility to the Blood Angels codex by giving us another set Warlord trait and a very assault oriented Troop. Cassor the Damned also helps out our limited Troop choices, but he's not as self-sufficient as the Death Company. I don't expect to see any of them dominating tournament armies, but you should definitely keep them in mind when putting together your army lists.