Actually had little doubt that 'Toys Will Be Toys' would work. It revolves around an incredibly charming premise, although not very original (being already familiar territory in animation) and it is hard not to dislike anything centered around toys. As has been said more than once though, the Screen Song series that it is part of is very inconsistent, with the same good things but similar bad things in most, and had seen a few pretty mediocre previous cartoons in a row.
'Toys Will Be Toys' to me works very well, is a lot of fun and is as charming as the premise suggested without trying too hard to be cute (something that a lot of cartoons in the series failed at doing). Two thirds of it is absolutely great, the other third not quite so much not unexpectedly. Again from personal opinion, 'Toys Will Be Toys' is one of the best of the Screen Song cartoons and easily the best since 'Little Brown Jug' which feels like a long time ago.
Do agree that it is at its weakest in the singalong portion. The song ("Oh, You Beautiful Doll") is absolutely beautiful and beautifully sung, but the cartoon does lose its energy at this point, literally coming to a standstill and becomes too saccharine. The material in this portion is also pretty flimsy and derivative.
Likewise that the cartoon is pretty much plotless which affects the momentum when the material becomes less inspired.
Which, we are talking again about the inferiority of the singalong portion, was not as much the case with the previous two thirds of 'Toys Will Be Toys'. As ever with the Screen Song series, the animation and the music are the best things. Is beautifully animated. The colours are vibrant and there is meticulous attention to detail in the backgrounds, the toy store is such an inviting and nostalgic place and the there is some creative animation on the toys.
If there was one aspect that was consistently good in Famous Studios' 1940s and 1950s output, it was the music scoring and it is outstanding here in 'Toys Will Be Toys'. The orchestration has a lot of energy and there are some truly luscious sounds throughout. The series has been very variable when it has come to its songs, but "Oh, You Beautiful Doll" is to me one of the better ones with its beautiful melody and that there is nothing sickly or annoying about it.
Regarding the gags, 'Toys Will Be Toys' may not be filled to the brim with them but there is no shortage of them and they are not as corny or as predictable as other Screen Song cartoons, they amuse too. Although the story is slight and loses momentum later, the first two thirds are full of exuberant energy and sweet but not too sugary charm. For the first time in a while for the series, the characters are ones worth caring for and are engaging in personality. Koko and Popeye's cameos are a delight.
Overall, not mind-blowing but very nicely done and one of the series' best easily overall and in a while. 8/10.