I came to this course after taking some parts of Harvard's CS50x (a really good course), another Intro to CS course, so I couldn't help but compare. This isn't to say which one "did it better"
(since you really shouldn't compare since they have difference scopes) but just to show you how they are different, and to help you choose depending on what you're looking for.
They take different approaches. CS50x explains a lot of what goes on "under the hood" and teaches programming using C (a low-level language in comparison to Python), and also touches on a lot of other CS topics besides programming. It's a more comprehensive introduction. MITx6.00.1x actually seems to avoid mentioning what goes on under the hood, because the focus is on abstraction and modularity, and uses Python to teach programming. Compared to CS50x, 6.00.1x lectures are more "bite-sized", discussing one or a few topics at a time then testing your understanding with finger exercises immediately afterwards.
The lectures in 6.00.1x can be somewhat dry at times. The problem sets are sufficiently engaging. They can be difficult while you're starting out, but they become more manageable as you learn more about the language.
In summary, if you're choosing between CS50x and this course, the points to consider (imo) are:
the approach ("under the hood" vs "abstraction and modularity"),
the scope (programming + touching on more vs just programming hence shorter),
the language used (C vs Python),
and length of lectures (1hr+ each vs ~10min lectures with fexes in between).
Overall, 6.00.1x did well the things that it set out to do.