1) Do we all absolutely get it? That would be fine, unless it starts like that and then it is decided that only some people should get it. I see this as a strong possibility: the rich already have enough, why give them more? This then falls under the usual debate about whether the rich should pay for everyone else.
2) I would be more open to it if it was run as a one year experiment. A problem with a policy like this is that once approved, it is very hard to take it back if it does not work at scale or unforeseen problems arise. What politician in his right mind would tell the population that they are cancelling the $500 check everyone gets once a month?
3) It takes away the need for work. I don't but the "flipping burgers at McDonalds is no better" argument. If UBI solves this problem, then there won't be any more people flipping burgers at McDonalds? That is bad because a lot of businesses will go under. For fast food restaurants to work, someone has to be willing to do that work. The idea that now everyone will be "free to explore more meaningful work" seems far-fetched to me. If everyone gets money, then prices will increase accordingly.