is bleach episode 300 filler?

Kisuke Urahara tells Aizen that it has been a long time since they last met, and takes note of the extraordinary form Aizen has taken. Aizen states that it's nothing, as the midway point of "evolution" is always ugly.

Urahara clarifies that no one has said he is ugly, it's just that he has finally fused with the Hōgyoku. Aizen explains that it isn't fusion and asks that the word "subdue" be used.

He then states that the Hōgyoku Urahara failed to master has found a new master. Urahara glares down at Aizen and remarks that it's true he was unable to master it, if Aizen is referring to the past.

Aizen questions his statement, asking him if he's going to admit defeat.