Component appears to have lots of promise, but doesn't deliver.
Version 2.1 has lots of flaws and other Joomlaworks products don't work with it without a lot of hard work debugging flawed code.
1) Company has never responded to any direct email
2) Company rarely responds to any questions raised in the forum.
4) Lots of promise of K2 V2.2 with bug fixes and additional features thus far not delivered.
5) Twitter about V2.3 when V2.2 isn't even out the stable yet.
If you want to waste large parts of your life fighting with this product then go for it, otherwise find another CCK.
An additional note to say that if "Open Source" wishes to become a viable alternative to commercial product, then for god sake fix deadlines, stick to them and keep consumers/end users informed effectively.
Forget promise and make actual deadlines otherwise those of us with a life and business to run will go elsewhere damned quick!
K2 v2.2 is here, bringing many improvements to an already successful package, powering some of the most popular Joomla! websites ever built, worldwide.
Regarding your other remarks... if you understood "open source", you wouldn't make these remarks as they are pointless. Open source is about quality, security and a whole lot more important words than "deadline".