I'm still a little pissed about the iCodex bait and switch on the army builder tool. There's apparently been a Facebook message from GW's digital division stating that "technical difficulties" with apple prevented the version with the new tool from being uploaded. They say it should be up some time this week. We'll see.
So Heldrakes still exist, and Marines got no Interceptor units. This is a serious problem, but otherwise the codex looks solid.
Chapter Tactics
I like pretty much all the various Chapter Tactics. The Ultramarines version is a little bit of a let down compared to the rumors. It's more situation than the others, but its better than a kick in the teeth. I guess it's OK since Tigurius is stupidly awesome to make up for it. My favorite is probably Iron Hands for army wide 6+ FNP and It Will Not Die on all characters and vehicles.
I prefer the Chapter Tactics that don't force your hand at army creation (Ultras, Iron Hands, Imperial Fists), but you can make some nasty lists around the others too.
Warlord Traits
Not the best, not the worst.
Relics
There's a storm shield that gives you eternal warrior for 50 points. And some other decent but overly expensive stuff.
Wargeer
Grav weapons are nasty, but skip-able on most units. On Tacticals it just doesn't gel with their range bands and the rest of their shooting. Do you really want to get a 10 man tactical squad within 18 inches of a T6 2+ nasty for only two shots? Take plasma instead. Bike mobility may make them worth it, especially since you can get two. The pistol seems to be a bit more universally usable but still expensive for a single shot.
Relic blades are way over costed. You don't pay 25 points for a melee weapon unless it's AP2.
HQ's
Tigurius wins at being a special character in the Marine Codex. He's got re-rolls out the wazoo, 3 powers, and only 165 points. None of the others seemed to have changed much in relative strength, but I may have been too blinded by Tigurius's awesomeness to notice.
The generic chapter master is much improved. 20 more points, but +1 to attacks and wounds. His stat-line now matches Calgar's. I personally like Iron Hands Masters with Sheild Eternal, Artificer Armor, and a Thunder Hammer. 4 wounds, 2+ , 3++, 6+ FNP, It Will Not Die, and Eternal warrior for 230 points.
The librarian came down in points, everything else had minor adjustments. Techmarines are one per HQ, and don't take up a force org slot. Still 50 points base for a 1 wound model. Space Marine Servitors are no longer the worst unit in the game. Honor Guard got cheaper, but not enough to make them worth it.
Troops
Tacticals getting cheaper was a lie. While the base cost came down, Veteran Sergeants and weapon options are no longer free. So a 10 man unit with Veteran Sarge, flamer. and missile is actually 10 points more expensive. It is fair to say that building the unit is more flexible.
Scouts are cheaper and can take Land Speeder Storms as dedicated transports. Stil BS3. Sniper scouts still have a place in some lists.
Elites
Cost adjustments all around here. I still think Vanguards are still too costly. Legion of the Damned are a lot more interesting. Not that much more expensive than Sterngaurd for a 3++, and all their ranged attacks ignore cover.
Fast Attack
I think Assault Marines came down in price enough to justify taking a unit. At least in Ultramarine lists where you can buff them for a turn. Bikes are nice too. GW really wants you to buy bikes this edition. They must have really high profit margins given that the molds are at least 15 years old.
Heavy
Shooty Centurions are nice. The grav-cannon setup has range issues, but I think their justified in order to deal with Riptide and Wraith Knight spam. Their point cost and lack of invul make them not quite over the top. Their a good unit to run in an Iron Hands detachment since the sergeant gets It Will Not Die as part of the mix.
I really like 65 point Whirlwinds. Especially when the tournament meta relies so much on hiding weak-sauce troops behind terrain in order to win games.
I'll pass on the new AA tanks. Ground based AA needs interceptor. Using your own fliers for flyer defense is a better option when you don't have it.
Conclusions
What to do about Heldrakes and cover ignoring Riptide Ion blasts is the trouble. I'm not seeing any good counters here and marines need em badly since the 3+ save is all they have going for them. It's just like the previous codexes where they give out a few shiny new toys to cover up that they didn't fix any of the basic structural problems with the army or the edition. Still the band-aids are enough to get them onto the table at least. And the grav weapons are enough of a hard counter to make players think twice about spamming Riptides and Waithknights. Unfortunately tying up hard counters in specific armies is not a good strategy for overall game balance.