I wouldn't exactly call that bike an investment. The low end full suspension (not soft-tail as wellbiked pointed out) bikes aren't worth much, and really aren't worth buying. The shock and fork on that bike are very low end and barely functional for serious off-road riding. If you're just riding it on the street, it's probably fine. As far as being worried about the bolts, don't just "tighten" them, you might break the heads off if you get carried away. If you're really worried, take the shock bolts out, inspect them, and then regrease and reinstall them, torquing them to specification (hopefully Windsor provides this kind of info).