I feel like you can never do justice to a book, and by extension a visual novel. Note that I'm not a "MOVIE SUCKS READ THE BOOK!!1" purist by any means. Film and anime adaptations can definitely be enjoyable but I think that in the case of Steins;Gate too much had to be removed. I think that much of what made the VN so interesting is Okabe's inner monologues which are largely absent from the anime from what I can remember.

The same can be said of another VN I like Clannad - and its anime (which I hate). Again, the best moments in Clannad come from Okazaki's internal monologues.

Also, there's the issue of routes. Best Girls Suzu and Tomoyo got neglected in their respective anime which was not that terrible in Steins;Gate but unforgivable in Clannad.