Is using this eSIM cheaper than my AT&T / T-Mobile / Verizon roaming plan?

Yes, in most cases. US carriers' "Roam North" or "Day Pass" plans often charge $10-$14 per day, which can add up to $100 for a 10-day trip. A Cellesim eSIM is a one-time prepaid fee. For the same price as two days of US roaming, you can often get enough data for your entire 2-week Canadian vacation, saving you significant money.