I am not here to say the new codex is good or bad but I'm already hearing people compare them to the new Chaos Space Marine (CSM) codex saying that Chaos is quite lame which I think is not right. I will say that for the most part up to this point in time based upon what I do know is that the new Dark Angels seems to a large degree to be a step back in time to what they had back towards the end of third edition with their FAQ by Andy Hoare that brought them in line with the release of fourth edition. They had nifty battle standards and lots of other things you'll see now in the new codex. GW takes away (thanks to Jervis Johnson) and now they have decided to give some back.
A lot of people will say that Dark Angels were always the red headed step child of the Emperor... That they were subpar compared to any other MEQ army. That's not true at all and one of my best armies was 3rd edition Dark Angels with their fourth edition FAQ. Back then you could take five man tactical squads with both a heavy weapon and special weapon - the de facto tactical unit was five tactical Marines per squad with a lascannon and plasmagun. They were Intractable so they never had to take a break check due to enemy shooting... They stood there shooting all game for really cheap and it was awesome. Deathwing was stubborn which almost as good as fearless back then (only had to take pinning checks) and terminators could take two assault cannons for every five terminators plus you could take terminator command squads so it was easy and cheap to spam assault cannons. Dark Angels back then were the best Space Marine shooty army and had very excellent counter assault units in the form of Deathwing (terminator) command squads. The Librarian was I5 with three wounds and could cast Veil of Time which allowed them to reroll everything - saves, to hit and to wound. A Librarian with a Storm Shield and Admantium Mantle was an Eternal Warrior, could reroll his 2+ armor save, 4++ invulnerable save, plus hits and wounds. They also had Furious Charge via their Deathwing command squad... Nothing could even so much as scratch them in melee.
The new Ravenwing
I have always loved bikes but at the end of the day you've got a small expensive squad with a 3+ armor save... They can die quickly to enemy shooting or in melee versus any superior unit and there are a lot of superior melee units. I've seen some great players try to reach the top tables with biker armies but invariably they always fell short... 40k is still to a large degree a rock paper scissors game and there are some armies such as Imperial Guard that simply shoot them off the table. The new Ravenwing is definitely strong but I don't see them as a pure biker army being any stronger than past armies such as White Scars. Black Knights are very good but they are also very expensive.
Dark Angels vs Chaos Space Marines
I hate to see people already comparing the new Dark Angels to Chaos Space Marines and saying that CSM is a poor codex. To me it's obvious CSM are intended to be played with daemons and this was always the way except for the last edition. Allies are very much a big part of the game now.
I think there was too much of a high expectation for CSM... They were the penultimate army back in fourth edition - more so than any army since then in my opinion. It's a big mistake to set them against that as a standard.
Sure Dark Angels have some bonuses versus CSM but CSM have access to Hatred versus any Imperial Space Marine army. CSM made out better in this regard since their bonus is cumulative versus a higher number of armies.
I like the new Dark Angels codex but it's much too early to make a statement that they are better than Chaos Space Marines.