I used it from iOS 15-18 and it always worked great. We try to limit our kids' iPad use to drawing in Freeform and the occasional edutainment app, and I never had issues with them escaping Guided Access or it causing lockups. The fact that I can barely trust it to work properly on iPadOS 26 is a huge disappointment for me.

I’ve never used it myself (no kids) but I’ve long heard tales of kids being able to get around it, it miscounting time used allowing too much use, etc.

It sounds really nice for the intended purpose, just not reliable for many.