Since no one's addressed it per se => From a content standpoint, the Aquan ships in Overseers are a little on the specialized side. The Oannes and Sulis (Sulii?) on the Aquan side, and the Turmoils on the Directorate side, can work fine in straightforward beginner use, but pick up substantially with experience and understanding of their special rules.
Which is all just to say that a regular Patrol Fleet Box would be more typical and straightforward. I see those basic Aquan cruisers and the super-economic Battleship as the mainstays of an Aquan build.
Buuuut, were I in your shoes and money allows, I'd still do the Overseer Box for the built in match-up capability, and the sheer value.