The media giant didn't say how many of those had signed up on launch day versus taking advantage of weeks of pre-orders. There's no question that Disney has been determined to get as many day-one customers as possible, though. The pre-orders included discounted three-year plans, and some Verizon customers (that's Engadget's parent company) will get a free year of access.
The real question, as you might have guessed, is whether or not this will translate to success in the long run. There's no guarantee that customers using promotional offers or one-week trials will commit once they have to pay full price, and it's unclear if there will be enough content to keep people watching once they've had their fill of Star Wars and Marvel movies. Disney+ is likely to keep growing, but the ceiling for that growth remains to be seen.
And it's important to stress that this won't necessarily hurt rivals like Amazon or Netflix. While there are likely to be some people who sign up for Disney+ instead of one of the alternatives, it could easily be a supplement to people who want to watch Disney's (many, many) properties alongside other internet-only originals. Subscription fatigue is real, but Disney+ might not be the service that drives people over the edge.