I am an owner of one of these cameras. I received it as a gift from my brother who has changed to using a digital camera. Basically it is a purely mechanical camera using batteries only for the light meter, so if you're out of batteries, the camera is still fully functional - ie. the same as the Pentax K1000. This makes it a great camera for backup if your main camera's batteries pack up - presuming you have a lightmeter at hand (I inherited a Weston Master II!) or know the F16 rule. You will be surprised at the quality of the camera: it apparently has an aluminum alloy frame and you should not be fooled by the plastic top and bottom covers. It is of sturdy construction and it will certainly give you many years of great use. My camera is of Japanese manufacture, and I have heard that they now are manufactured in China . I cannot confirm this but if it is, I do not know how the quality of construction would be effected.
One thing that I can assure you is that you have a camera of much greater quality and with greater capabilities than most early photographers had. My Vivitar has seen a great amount of use and do not show any more sign of use than my Canon A1 or Yashica 635, because I treat it with the same respect. I am sure that it would be more badly damaged if dropped, but that would not be so much the fault of the camera as of the user (and I would assume that any camera would not take a drop lightly). I must however mention that the paintwork of the Vivitar is not that great, already showing signs of deterioration.
Because it is such a simple fully manual camera, you do not really need an instruction manual. A good book on photography will be sufficient to get you going for many good years of enjoyable photography. The 28-70mm zoom lens on the camera delivers sharp images. I think that for the price it is a bargain and it will turn out to be a much greater investment to you as you may have thought - especially after the more negative comments that I read in this thread.
Cheese it and enjoy it!