Is Helium Mobile really unlimited data?

Excuse me, could you please clarify something for me? The advertisement for Helium Mobile claims to offer unlimited data plans. But, I'm wondering, is this truly unlimited with no hidden fees or data caps? I've heard of other providers advertising unlimited plans only to find out later that there are speed throttling or usage limits. So, I'm hoping you could shed some light on this and ensure me that with Helium Mobile, the unlimited data claim is legitimate and there are no surprises waiting for customers. Thank you for your time and consideration.