The main problem with The World God Only Knows -- which is a mouthful, so forgive me for using acronyms from here on -- was its infuriating arsehole of a protagonist, Keima. Unsurprisingly, a lack of Keima makes this short Kanon spin-off infinitely more enjoyable.
Some fans are undoubtedly going to disagree (and I will call them crazy for doing so), but in my case, Keima nearly ruined the entire third season by the sheer force of his twattery. Even before that, he was only marginally more tolerable. TWGOK has always been a series whose primary appeal has been the cuteness of its female characters,
and Keima by his very nature obstructs this by coldly manipulating all the girls, treating them like disposable objects, a means to an end, an outlet for his sadism. The OVA is a nice (albeit temporary) step forward for the series as it focuses solely on the moe appeal and removes the plague that is Keima.
The only real issue is that Kanon herself is a dull heroine. Oh, she's cute - there's no doubt about that - but there really isn't much else to say about her beyond that. And 'cute' is a trait that can be easily found in thousands of other anime heroines. The OVA likely focused solely on her moe power because, well... there isn't anything else that can be done with her.
Kanon's moe power is merely intensified by her transforming into a loli for the majority of the OVA. That's always nice for viewers who are fans of little girls, but personally it is not my sort of thing. I prefer my girls at an age that won't land me in prison. Maybe I'm just the weird one.
The story of the OVA is largely boring and inconsequential, but that shouldn't come as a surprise given that it is not a part of the main series. While it is not bad any means, it does take away time that could be better spent on what every single person watching it wants: Kanon doing cute things. And looking cute. And saying cute words. See, I don't even know what the hell else to say about her.
Also, why she is even a loli in the first place or how she (inevitably) returned to normal remains a bit of a mystery. Even more baffling is why the dozens of people around her who witnessed MAGIC and other forms of craziness do not seem to care afterwards. Then again, TWGOK is not a series that ever attempted to carry any sense of realism, so I suppose all this is moot point.
The art and music are fine, but anyone expecting more of a movie treatment are going to find themselves incredibly disappointed. Considering Kanon's idol career, it would have been nice to see her concerts in more detail, but there is nothing of the sort unless 30 seconds of stills qualifies as 'performance'. If nothing else, at least it's visually consistent with the main TV series.
"Magical☆Star Kanon 100%" is a nice little treat for TWGOK and Kanon (no, not the show) fans, but if you didn't care much for the series then I can't imagine there's anything that will change your mind here. It's one of those things that simply exists, neither impressing nor offending anyone. It is the epitome of average, a rock on a hill.
At least there's no Keima. And more Elsie is always appreciated in my book.
the new kanon OVA has been quite a wait for kaminomi lovers, this OVA is pretty good as it is able to give a fairly good overview in one episode, however the story itself is a bit wishywashy and lacks depth or backing to what is happening, the songs are great are to focal point of the OVA,
Overall I thought it was enjoyable but it could have been more effective with more episodes much like the manga hoever it was still quite good for a spin-off OVA