Personally, I think it was during 43-46 period when Judy looked and sounded the best. And incidentally, it was also the period when the classic MGM studio system was at the apex of its efficiency in churning out one great musical after another before its demise later in that decade.
In Good Old Summertime, one can't help but realize, with much regret, that the greatest period of the good old musical films and of Judy Garland was beginning to wane. And it is noticeable from quality of music scores and from changes in her appearance also.
Of course, it's still a very enjoyable movie, especially if you watched one of the other movies based on the same story. And Judy still looks amiable and sounds great even when she had to sing in such self-deprecating manner as in 'I Don't Care', which feels very different from other instances of similar comic approach of her previous films like 'When I Look at You' in Presenting Lily Mars, or 'Couple of Swells' from Easter Parade, for example.
Even though the movie is categorized as a musical, it's certainly not Harvey Girls where you can enjoy such trademark MGM scenes, like that big, complex sequence as 'Atchison Topika and the Santa Fe'.
Back then, the Freed Unit with so many talented actors and actresses were so efficient that they didn't need too many camera cuts or even extensive rehearsals to create a such captivating 20 min long sequence.
In Good Old Summertime, Judy Garland is almost the only person who sings, and there is no 'sequence' to talk of, as most of the numbers are done by her singing solo, except for the Barbershop Quartet and 'I Don't Care' numbers.
In general, songs are less memorable than those from her other movies. There's a Christmas song which Judy sings beautifully as usual, though it just isn't on par with 'Have Yourself a Merry Christmas' from Meet Me in St. Louis.
Judy still looks attractive, but not more so than in her earlier movies. Her personal troubles in real life begin to take their toll on her appearances by the time she appeared in this movie. Van Johnson is amiable, but he's certainly not her ideal partner in a musical film, as he can't really sing or dance like Mickey Rooney or Gene Kelly.
All in all, it's a still very enjoyable movie, but if you are a Judy Garland fan like me, you might want to try her other films first, preferably one from the 43-46 period, if you haven't seen them all already.
And when you have already seen most of them, and when you are sure to understand why people keep praising Judy Garland and her movies from her better days even today, then with a preparation of your mind for experiencing some regrets and pangs which might result from seeing her lesser self in a lesser kind of a musical, you are ready to enjoy this movie as a devote Judy Garland's fan.
It's something similar to what it requires to enjoy her late year recordings like the famous Carnegie Hall album. It pains to notice how she lost her range and her once impeccable vibrato became one that sounds artificial and forced.
But at least, it's Judy Garland and I believe that would suffice to enjoy it for most her ardent fans. As to what seems deficient, they can supplement it by their memories of what she has been in her prime time.