Well I'm a big fan of them, always fun to play with how fast they can move, firing off bolt and plasma pistols before charging in and putting xenos and traitor to the chain sword.
From the competitive point of view many players don't use them as bikes are superior in many ways for ~ points.
Just as fast, higher toughness, and twin-linked on the bolter + range. Then there is the whole Ravenwing thing.
But Dark Angels do have assault marines in the chapter so it would not be out of place to play them.
I prefer the packs as they give mobility though the entire game. A pod will slam down and get you there, but if they live then what?
Size is also an issue- a big pack of them, the most fun to play needs cover to jump behind and lap-frog over- preferably LOS blocking cover, but you can also scoot them behind a land raider or razorback/rhino if smaller in size- and with the packs they can keep up if the vehicle zooms, and they can break off to intercept incoming stuff or add some additional punch to whatever is in the land raider or rino.