I also found it silly she had to be included in the book but I agree with SM and Hicks. A lot better than I expected at the time. Ripley didn't ruin the experience for me, I even enjoyed the way she was written. Literally the biggest problems with the book I have is the harpoon-gun and number of cryotubes.
On the other hand, River of Pain really annoys me like no other entry. It has really good bits but the bad ones make the whole thing sour for me. The premise was just stupid even though the writer wrote some characters pretty well and I did like his take on the aliens. But the inclusion of marines (not the writers fault though), the contrived escape ship, over usage of scenes from Aliens, messing up the Derelict's layout, reusing Newt's Tale and other stuff really pulled me out of the story.
As far as retroactively adding to the lore, I do agree that Alien Isolation and Out of the Shadows are good examples, the best IMHO.