Who else besides Ichigo has a transformation bankai? I know that in the Seireitei there are many different kinds of bankais and was wondering if Ichigo is the only one that full on transforms when he activates his bankai.
I found Sode no Shirayuki (袖白雪) / Hakka no Togame (白霞罸) to be worthy of being called a full-transformation Bankai.

Depending on argumentation, you could also classify the newly revealed Bankai of Zaraki Kenpachi as a full-transformation Bankai. Even though the specifics are unclear as of now, the artwork suggests it has a similar mechanism like Ichigo's and Rukia's Bankais.

Additionally, there are a few that partly transform the user, as mentioned in Dimitri's answer.