I was also greatly annoyed by the ending.
I didn't mind much that the whole body switch thing was pretty downplayed pretty early on.
But I don't really mind it just being a plot device to put a weak nerd in a martial artist's body. It's fine, it gave some fun situations and overall was entertaining.
The ending was just stupid and no matter what is said can make it better.
It's even so stupid, I have decided for myself that the last arc never happened and the ending was that one chapter where he went on a boat ride with that girl whatsername, the last chapter before the raping began.
For anyone who is planning to read this, stop at that chapter, At least let it end when it was still good.

Do but despise reason and science,
The highest of all human gifts -
Then you have surrendered to the Devil
And must surely perish. - J.W. von Goethe

I thought it was a really good siries. It had its ups n down but overall it was a fun enough read. True much more could have been done to make it more interesting, especially the ending, but it wasent all that bad. Its really just the last few chapters, felt like things where rushed to a end. Which I suppose they where, was probably cut and the author was forced to end in a few chapters.

Wow over 10 years ago and I just finished with such a disappointment of an ending