I didn't think it was filler at all.
Last night showed that Skyler is a scheming ass bitch, just like Walt. Not to the same extent, but she rattled off numerous scenarios for getting the kids out of the house, and then revealed that her ultimate plan is waiting for Walt to die.
It set up so many different scenarios that could play out. Skyler COULD be driven to kill Walt. Walt could drown Skyler in the pool and it be ruled a suicide.
Hank is exhausting all possible avenues for finding Heisenberg.
Yeah the episode didn't have a lot of action, but it was entertaining drama (the show is a drama after all). This episode can lead to a lot of action, so it did its job.