South Park did the EULA gag, and such an agreement would be unenforceable as unconscionable. NDAs, on the other hand, are conscionable, but a EULA isn't an NDA. There isn't a specific statute that you can point to that either makes such a no-criticism agreement explicitly legal vs. illegal, so the case would have to be based on common law justice-style arguments. People v. Network Associates is a relevant case, where a clause requires permission to publish benchmarks or reviews of the software. The court found against the publisher. However, the restrictive condition was not part of the license agreement, which included a merger clause that declared the license agreement to be the whole agreement. The publisher had some hand-waving about mention of "rules and regulations" which they argued nullified the merger clause, where the court did not accept the argument. So for the moment, you need to decide whether disparaging a product is that important to you; or, become a legal pioneer and win a case in court.
There is a bill, the Consumer Review Freedom Act under consideration (passed the Senate) which might change that, if it becomes a law. It pertains to
a written, oral, or pictorial review, performance assessment of, or
other similar analysis of, including by electronic means, the goods,
services, or conduct of a person by an individual who is party to a
form contract with respect to which such person is also a party
a contract with standardized terms—
(i) used by a person in the course of selling or leasing the person's
goods or services; and
(ii) imposed on an individual without a meaningful opportunity for
such individual to negotiate the standardized terms.
which says that that kind of contract with that kind of provision is void.