From the perspective of someone who has no intaraction with the forum (my dad) and so sees it as a new user would.
I bought it for him and explained (a couple of weeks ago) what was new and had been completed and what was still to do when compared to v2.6 (IE. 3D background and new fish / clock etc) and he said he won't bother downloading it until all the new stuff is completed.
He previously has seen the old versions and doesn't see the 3D background as much of a difference (he slows it right down same as me) so he will really only notice the new fish models.
You need to be very careful when releasing this, as it is now not a singular good product in a bland market, there have been many copies of your aquarium. It has been 6 years since first hearing about the 3D background, I would be interested to know how much of that time was really developing this and programming it? and how long before the basic product is finished (new fish models / behaviour). because I don't think that releasing it unfinished will get many people buying it but neither will waiting six more years.
Not sure how much of this is useful feedback
but I am buying it on expectation of your usual quality and loyalty to the product, my dad as a new user isn't.