We have a Toys'r'us bike shaped object in our collection... we bought it before we knew anything about bikes, for my daughter - we allowed her to choose - so of course she choose a dual suspension BSO. We have since offered to buy her a new bike ... but apparently she likes this one. (I'm still looking out for one to tempt her - she doesn't ride much - basically when we do family rides but it probably has to be a trendy PINK!!! for a teenager).
Its very very heavy, and when we have tried to adjust brakes, or anything, its impossible. We have contemplated upgrading bits but honestly there isn't one bit of it that I wouldn't replace so its not worth it. For example the screws that adjust the brakes are very flimsy and loose, the bearings went in one wheel probably within 50 to 100 miles.
I'd say don't touch it - I wish I'd had the benifit of hindsight. (The only thing I don't regret about buying it, was it was the first time I had access to a bike that I could ride, and that's when I discovered that I enjoyed riding a bike ... so I guess I'm not sad that we bought it).