'Popeye's Mirthday' is a cartoon where there is no Bluto (not a bad thing and the series proved more than once that it could make good cartoons without him) and with only three of Popeye's nephews. While the premise is hardly an original one, Popeye and Olive Oyl have such great chemistry (obvious in the 30s in the cartoons where it was just them and likewise later on) that works so well in this sort of story so there was little doubt in my mind that this would be at least above average.
Above average 'Popeye's Mirthday' is, 1953 was not the best of years for the Popeye series to put it lightly but this is one of the better faring cartoons that year. There may not be much new (though there were certainly far more formulaic cartoons that year), but it was great to not see Olive underused and to see the nephews have good intentions and really want to do something nice for their uncle. 'Popeye's Mirthday' couldn't have been a more perfect scenario for this.
It's not a perfect or great cartoon, though nothing is done catastrophically. Actually, despite the synopsis, thought that the nephews' methods of distracting Popeye while very entertaining and well timed could have been more creative and had more variety. The nephews are actually fine in characterisation, but their character designs in colour never quite did it for me due to being too primitive.
On the most part, the animation is bright and colourful but like a lot of Popeye cartoons in the 50s it's also uneven. It's colourful and with some nice details but can look a little rough and rushed looking.
There however is one aspect that is particularly good and it's something that has always been a major bonus in the Popeye series. The music score is more than just good, instead it is typically outstanding. It's beautifully orchestrated, rhythmically it's full of energy and there is so much character and atmosphere, it's also brilliant at adding to the action and enhancing it. The gags are nothing original or creative but they are amusing at least and the cartoon is not short on them.
Furthermore while the story is admittedly very formulaic, it has a lot of energy too. All the characters are written well, especially the nephews this time, and the voice acting is very good.
Summing up, not great but pretty good. 7/10