Realistically...
Just to address your points:
1. There is support in open source. You have to pay for it like you do with M$ or Apple. The difference is that it's much cheaper in open source.
2. The interfaces are not much different than Apple or MS. As a matter of fact the new Unity interface has quite a few similarities with Mac OSX.
3. I had one bad experience with a Perl forum where I submitted a question about some code I wrote and got my hair promptly removed by the blast of hot air from their responses about how it was stupid and could have been done better even after I told them it was my first attempt and to give constructive criticism. But, haven't had that problem since in all the time I have been using Linux.
4. I agree with this. Up to now there has been no motivation for free software authors to continue their work and would just let it die. But, Ubuntu has done a great thing by creating a venue for developers to sell their product and to provide reviews by people that have used it. I think this problem will fade away as more developers use the online store approach. Also, if they want to sell their products they'll bump the quality unless they want a bunch of bad reviews.
5. Don't know about the other products but this was my first experience with Suse Linux about 10 years ago. Things have changed now with Ubuntu's (and probably other distros) package managers. They resolve all dependencies and install everything that is needed. They still need to get completely away from things like proprietary drivers that cause you to have to re-install them every time you get a kernel update. Still, there may be issues from time to time when conflicts occur of knowing what to do. You don't know if it should replace a library or keep it and you shouldn't have to know.
Generally, things are improving but they still have a ways to go in order to be as usable by the average Joe user as the other OSes.
