They have a really great app with multiple "storylines" for each item, so I personally didn't think it necessary. But if you don't have the app or don't want to use battery, then I'd recommend a guide. It's pretty mammoth, even though it's not crowded with items to view.
That said, the exhaustive "timeline" exhibit is really self-guided, and the victim memorial you'll want to explore on your own.
"Hey little girls, look at all the men in shiny shirts and no wives!" - Jackie Hoffman, Xanadu, 19 Feb 2008