I bought this lens in 1997 when it was the first 28-300 on the market. It is very large but produces good photos. I rarely enlarge bigger than 4x6 and have no illusions of being the next Ansel Adams. At 4x6, prints appear VERY sharp. I had an 11x14 made once that I was very satisfied with. I'm a serious "snapshooter".
This lens doesn't close focus but otherwise I like it a lot. It carries a 5 year warranty which I have had to use. The first lens was blurry and Vivitar replaced it when they couldn't align the elements inside. The CPU went out and Vivitar replaced the CPU. Customer service is very good from Vivitar, only $3.50 postpaid return.
77mm filters are pricey and it is a physically large lens. It doesn't creep. The front does rotate and you have to readjust the polarizer; not a big deal.
It focuses very quickly with Nikon AF bodies, even in low light. It does weird things on my Nikon N90s; rocking it back and forth works so I suspect a contact glitch. Works perfectly on F4 and F100. It manually focuses easily, also, on non-AF bodies.
I use 800 speed Fuji Print film and have no trouble handholding the lens even with heavy overcast.
I have ordered a Tamron 28-300 bacause it does close focus at 10", 1:2.9, and is physically smaller. I hope it is as good or better; if not, I'll return it.