The full loadout of this unit is as follows:
6 x Bikes
1 x Flamer
1 x Power Fist
1 x Attack Bike.
Usually they run with a Wolf Guard on bike to prevent the headstrong ruling becoming too much of a problem. These guys still want to get into close combat where possible due to the amount of attacks they can throw out. The flamer in there helps to negate the BS3 of the Blood Claws, while the twin-linked bolters help to diminish the low ballistic skill even further. And with the Space Marine bike having the relentless rule, these guys can shoot then fight their way through a target unit in no time at all.
Due to their speed the Swift Claws can cover a lot of distance around the battlefield, and benefit from a 3++ invulnerable if they turbo-boost in their previous turn, which can become invaluable if your opponent identifies them as a serious risk and turns their heavy weapons on you.
The greatest problem I have faced with this unit is that when fielded at its full size, the physical dimensions of the squad make it difficult to keep them fully covered from the enemy. Having them shielded by a Land Raider can be a viable option, which leaves you with two expensive units running together, but ones that should be able to tackle most things in their path.
As for their most impressive feat, it has to be wiping out almost three squads of Necron Warriors, almost single-handedly forcing the phase-out of that army.