This show came out at the wrong time. In the early 1980's the audiences were not ready to see how a senior copes with a change in lifestyle and how different generations cope with living with each other. Twenty years later with the baby boomers reaching retirement, things have changed and I think this show would have been a hit if it came out now.
The show had its problems with uneven writing, but given time it would have found its voice. The actors were all superb. Mickey Rooney pulled off the role of the grandfather very believably. Even though I am of a different generation, I could understand his confusion and joy living with two young people and seeing how many opportunities were open still to him. Dana Carvey and Nathan Lane playing his grandson and his roomate, respectively, carried off their roles believably as two young men not quite knowing how to deal with their senior citizen roomate. You could see the love and respect they had for him, though, throughout even though this was a comedy. Scatman Crothers was good as always, but the writers did not smoothly integrate him and his comedy into the storylines sometimes. A young Meg Ryan also appeared in this show as Dana Carvey's character's girlfriend.
It is too bad that the show left so soon. I only remember enjoying a few episodes before it was pulled. My parents and I used to make a point of watching this show every week.