The Handyman planes were, as the name says, their less expensive weekend handyman line. As Rob said, they can be tuned up and made to work well enough. Their value in money is not very high, but there are values measured in other than money. I'm sure that if you clean it up and tune it up you will get many hours of enjoyment from it. There are any number of tutorials on the internet for refurbishing old planes. [link:home.comcast.net/%7Erexmill/planes101/planes101.htm|This Site] has some good info.
As has been said, these were Stanley's lowest line of planes. Even so, they can work nicely.
The Handyman below was given to my wife. You can somehwat see in the first picture how poorly the bedding of the blade is--red jappaning that is all bumpy. Really needs to be filed and or sanding smooth.
This plane needed no more to work well than mentioned above. Now, the adjuster has more backlash than a better made plane. The rion was swapped for a better Hock blade which requires less honing as the edge lasts longer. The handle had the sharper edges relieved.
But it doesn't really perform any better. It can now take an even 1 thou shaving versus the 1.5 thou she achieved. And she prefers using the better LN/LV planes. But this one still sees use.
One of these guys? They tune up well enough, but it takes a little work. I'm not positive, but I think maybe they were made ~1960's. This one is the only smoother I had for a while, and with a sharp blade it worked well enough for me.
I, too, think it's a risk. You could dado the shelves in, but only glue them on the back (or front, or maybe middle) 1/4 or so of the joint. That would leave the balance of the wood free to move. If...