The plot of "The Return of Ironside" serves as a justification for getting all the old characters from the TV series together to solve a mystery again. As police procedural, it's better than competent; as a murder mystery, the solution is translucent, like a window in a bathroom, but it's still a puzzle. But for those few of us who loved the original Ironside character, just seeing him work again is a kick.
Raymond Burr holds the distinction of starring in not one but two of the best written, best produced and best acted mystery dramas TV ever produced; Perry Mason was the first; Ironside was the second. Just as no one will ever play Perry Mason again, no one will ever play Robert T. Ironside again. Burr made a whole slew of Perry Mason movies before he died; Return of Ironside might also have been the first of many had he not died of cancer shortly after filming.
All I can say is I've watched the movie half a dozen times and I still lik e it. It's not one of the greatest movies ever made; it's not even one of the greatest TV movies ever made. But just as the TV series Ironside was better than most other cop shows, the movie is a lot better than most other cop movies made for TV in the last decade or two. If you don't like Burr, you won't like it; if, however, like a lot us born before JFK got shot, you like Raymond Burr, it serves as a great ending for one of TV's best actors.