This is a very good manga, even if you don't know anybody with autism. If you do, the manga has little blurbs of advice interspersed with the story, which I thought was a nice touch. I noticed that there is never any trouble with insurance, or tuition, because it takes place in Japan. One area where the story was sometimes not very realistic: Sachiko is often looking to choose a daycare/kindergarten/school for Hikaru. When this happens, there is usually a daycare center that treats the disabled kids really negligently, and then there is one that treats them awesome. She rarely sees any schools that have both goodand bad things about them.
People who have not read manga before can still feel comfortable with reading With The Light. The best example of this is the sound effects: Rather than replacing the kana with English, or putting a cumbersome glossary of SFX in the back, the equivalent sound effect is written along with the kana. So next to ビュッ (byu!) is written "whoosh!".
The characters are believable, and overall it's a pretty well-done story!