Warren,
I can't really add anything to the comments that have already been posted. All the guys who chimed in already are about as knowledgeable in these matters as they come. I would only echo those who suggested that you use the plane. Your dad gave it to you. That alone makes it worth the effort.
You'll read a lot of things online about hand planes. One particular site that you may have visited, and is fairly well known, provides some really good information about Stanley planes. The writer most definitely knows his stuff when it comes to antique Stanley planes and other tools. The site is mostly a valuable resource but that's where it ends for me. I don't really get into the sarcasm or the overly negative, biased comments, that are intended as humor. I actually think they detract from the end product and unnecessarily cloud the subject with inaccuracy. Your plane, and that particular model, is far from junk. It was a basic plane, designed to do basic everyday work, while still being affordable to the masses. In gem mint condition, it's still not very collectible, or worth a lot of money. Because of that, some with a "collector's slant" may refer to it as junk. In terms of overall utility, function and affordability, it hit dead center on the bull's eye. Collecting planes means more than just acquiring perfect examples. I think it also means collecting history and appreciating design, function, and intended use.
Use your block plane and make up your own mind. Understand its design, limitations, merits and history. If it delivers good results, as initially intended, then keep using it.
Jim C.