The OpenBSD people in general and De Raadt specifically are probably the best-known objectors to Apache-2[1–4], among other things because they hold that Apache-2 is too broad to be a copyright license and thus has to be interpreted as a contract instead.
I don’t know if they’re right, but their arguments did shift my opinion in their direction.
Corporate lawyers seem to love it, though, because of the mutually-assured-patent-destruction clause.
> among other things because they hold that Apache-2 is too broad to be a copyright license and thus has to be interpreted as a contract instead.
Which is inane because a copyright license is a contract anyways. My understanding is that the number of lawyers who agree with the OpenBSD position is approximately 0, even in jurisdictions that don't have Anglophone interpretations of contracts and copyright--I haven't seen any lawyer come it in favor of the OpenBSD interpretation here. (Note too that criticism of the GPL doesn't include this--and if Apache is too complicated to be a copyright license, the GPL certainly is.)
There is also a certain irony in arguing that clarifying the terms of a license great yields less clarity than not doing so.
I don’t know if they’re right, but their arguments did shift my opinion in their direction.
Corporate lawyers seem to love it, though, because of the mutually-assured-patent-destruction clause.
[1]: http://www.openbsd.org/policy.html (see corresponding section)
[2]: https://marc.info/?i=91077.1475036864%20()%20cvs%20!%20openb... (De Raadt rants on openbsd-misc, discussed on HN at https://news.ycombinator.com/item?id=126178810)
[3]: https://lists.llvm.org/pipermail/llvm-dev/2017-April/112300.... (Kettenis objects on behalf of OpenBSD on llvm-dev)
[4]: https://www.cambus.net/the-state-of-toolchains-in-openbsd/ (OpenBSD gives up on staying with old LLVM)