Anyone else out there wanting to create a non-trivial Joomla! site, relying on ACLs for view and management control, don't think twice. ACL Manager is THE tool for this job and the price is very cheap, considering the huge time savings you get.
Well done, Sander!
Full disclosure: I personally know Sander and I was given a free copy of the extension as soon as it went live. However, everything I've written above is my honest opinion after having used the component on two sites (one test site and one real site I'm building).
There are a few rough corners but, in all fairness, not only it is an early 1.0.RC5 but speaking with the developer made me feel absolutely confident that they'll be ironed out very soon.
This is THE forum component, if you ask me. Very well done!
K2 is one of the most mature content management components for Joomla!. It does have a steep learning curve, mostly due to the sheer amount of options (and a somewhat disorganised documentation section). However, investing time in it will most certainly pay back! Each of those daunting options will quickly become your best ally to building a news site, your documentation section, a downloads directory, an e-shop, ... You name it, K2 can do it!
I was a skeptic when I first tried it. Now, I can't imagine building any kind of site without K2. The fact that this extension won the J.O.S.C.A.R. award at J and Beyond 2010 just speaks for itself.
I recommend it without hesitation or second thought to every Joomla! developer.