I used MongoDB last year and it worked fine for me. (I maintained it for about 9 months.) But of course I can't generalize that to other people's experiences, so YMMV. ;) I just used it squarely in the use-case which everyone mentions — many "well-behaved" writes which occur when no one's reading. Multiple replicas. Leveraged its indices. It wasn't an authoritative source of data, so in principle I could repopulate it. Dealt with failure modes, so missing data wasn't catastrophic.
I think articles like this are useful; when evaluating software, one thing I do is assume it's buggy and its proponents are deceivers. (Whether or not they intend to deceive. I can imagine being corrupted by wanting something to be true.) So among other things, I hunt down criticisms. Had this article been around last year, I'm sure I would've found it a useful hub in doing this due diligence.
(The actual thesis, of what the version number should be, is not so important to me... Version numbers are in some sense arbitrary.)