I'm relatively new also (3 years, 1K posts) and I'm also on the forums most days, some for way too long. Overall AK is pretty good I think - good reference info in the old threads and (mostly) helpful facts for questions. This reference info is far from complete and also somewhat difficult to find, so new postings are still very valid and repeated/partially repeated advice by veterans is still necessary.
I see AK as a metaphor that reflects some of the social dichotomies of our age (young vs. old, new vs. vintage, rich vs. poor, thrifty vs. spendy, faith vs. science, etc.).
It took a little while to get used to things, especially that there are some hot buttons and there are some members who are stubborn and/or have sharp elbows. But overall it's very positive. I don't see a decline in activity really. If there was one way to improve it I suggest that new members be welcomed more explicitly, and perhaps veterans should be more reserved with new posters so they aren't overwhelmed by conflicting advice.