I feel I should throw my two cents in and mirror what Ralph said. While I personally love the 3d background...and everyone here in the forum can appreciate the fine detail, artistry, subtleness of the effect and the enormous time and effort you put into it... the world of computer graphics...and screensavers has gotten a lot more sophisticated in the past 8 years and expectations will be raised.
I feel that releasing 3.0 with the same fish as the 2.x feels like half a new product. I personally would wait till the fish were overhauled and movement made more realistic. I have a feeling that people that pay to get 3.0 will quite possibly send in a lot of emails saying they just paid for 'half' an update...it simply doesn't feel 'complete' without those new fish.
Most not active in this forum will not appreciate the time and effort you took to create the 3d background and will simply see a new background and same fish and feel unsatisfied.
This is just my opinion of course and I reserve the right to competely change my mind at any time. It's also free and probably worth half that.
