GUID: varchar(36) versus uniqueidentifier

I'm working with a legacy database that stores GUID values as a varchar(36) data type:

CREATE TABLE T_Rows (
    RowID    VARCHAR(36) NOT NULL PRIMARY KEY,
    RowValue INT         NOT NULL
) 

INSERT T_Rows (RowID, RowValue) VALUES (NEWID(), 1)

I would assume that storing a GUID as a uniqueidentifier would be preferable since it's only 16 bytes in size as opposed to 36.

Are there any advantages to storing a GUID as a varchar?