I more or less share your opinions. It's certainly not my favorite from that time period, but I have seen it a few times. It's been very influential so I think it's a movie that genre fans should see. I think the prolonged rape and castration scenes are what got it the notoriety it has, but I'd say all these years later it doesn't quite pack the punch it must have when first released. Run of the mill horror and so-called torture porn movies of the last decade or so have far more disturbing stuff in them. Some of the later giallos like New York Ripper have it beat by miles as far as disturbing sexual content is concerned, and even some of the 80s slashers like My Bloody Valentine have as much or more gore. And then there's all the foreign stuff like August Underground, Mermaid in a Manhole, Vomit Gore trilogy, etc.

For the time period, I think Last House on the Left is a much better and more entertaining film.