Not a review, so much as some background information on this OVA.
There's a lot of misinformtion going around about this series, and it can be confusing to follow what order things truly go in. It's my understanding thar this special episode is commonly referred to as 11.5 of the first series, Happy Lesson.
This episode focuses on the main char, Chitose, and the side char Kanna. Kanna tricks the main cast aparrt into attending a free vacation at a Hot Springs, with a fake Chitose, while she tries to capture him in their absence.
A puppy is injured by a passing car early into the OVA, and rather than capture Chitose, Kanna ends up spending time with him, taking care of the puppy. It's a good little side plot, but the problem is it's often mistaken as being episode 12.
Where this OVA fits into the main story is debatable, the wikipedia states that "it's an episode originaly from Happy Lesson Advance" but this seems unlikely, as characters from that series are ommited, despite Kanna's efforts to "remove all the girls who surround Chitose"
In my opinion, this is simply a one-off side adventure, to be fitted chronologically in at some point between episodes 6 - where Kanna was introduced, through 10. Despite the popular opinion being 11.5 as stated above, references to Kanna's past attempts made to capture Chitose heart made in episode 11 would indicate this special is prior to that one.
Further reference with regards to this anime can be found at the wiki page: