I'll start by saying that I genuinely enjoyed the series on a superficial level. It was quite funny for the first half of the series, but as things became more serious and more 'H', the comedy, and the manga as a whole, began losing its flavor.
I wholeheartedly agree with user 'decisions' in that I was very disappointed with Mako's choice in the second-to-last chapter. It was a huge letdown, and felt like a knife to the heart.
The latter part of the series is a torrent of revelations and discoveries, but you'll have to take some developments with a large amount of sugar (not salt); it can leave you bitter.
Unlike other viewers, and the reason I'm rating this strange and ero series so high, is because I really enjoyed the ending and the characters Hiromi and Makoto. There could easily have been another chapter of prologue, a la Love Hina, which I'm sure would alleviate some readers' concerns about the abruptness of the ending, but I feel like the mangaka did a great job of tying things together, even though things got quite messy towards the end.
If you're a fan of futanari and/or frivolous lulz, look no further. This series is plenty 'H', but don't expect the full monty.