MASH was always a hybrid of comedy and drama, and some say it swayed too much towards the drama in the final seasons. Yes, it could be preachy, but it also found the right tone at times, like in this episode.
At first it seems a gimmick episode: everything is seen through the eyes of a wounded soldier (who can't talk). We get his entire stay at MASH 4007 from his arrival at the compound up until his departure. This shows us the familiar characters at their professional best: Radar, calming wounded down, the doctors finding a balance between reassuring flippancy and earnest bedside manner, etc. By sheer coincidence I saw this episode the day after spending several hours at an emergency room with an elderly family member. The clever way in which Margaret Houlihan distracted the patient with small talk while performing her (embarrassing) duties were extremely recognisable. That's what makes this episode special: you could believe that these professionals knew what they were doing. (In some episodes you wonder how those drunks could function properly.)
Perhaps not the funniest of episodes and Colonel Potter's plot line was a tad predictable, but I felt glad I had seen it.