The below sentence is wrong. I do not know why. It reads funny. I'm not an english expert, but...
This website was first on the list of priorities and your feedback over the past two years is much appreciated.
Perhaps the bit that bothers you is
...is much appreciated.
There's nothing inherently wrong with that construction, grammatically or sematically. But I think many people might say it would read more 'naturally' if you changed it to
...has been much appreciated.
That will get rid of the slight unease created by the sentence switching from past to present tense.