Probably one of the hottest topics around at the moment! And it may well end up as a "Beta vs VHS" argument in that the best one may not win, but the one with the biggest user base and community.
K2 would certainly seem to be winning in terms of promotion and usage from what I see.
I have just built my first site using K2 (
www.no-bull.net) and Joomla Bamboo's Avanti template. I must say it's a bit like riding a BMW 1300 motorbike. The harder you ride it, the more power you find it's got. I don't think I've even touched the surface yet though as I chose a very simple site to start with.
A couple of issues I have found however, some of which are a bit concerning.
1. Traditionally in Joomla, if you use h1 tags in your Header, then you can set sh404SEF to convert the title tags to h1 also. This doesn't seem to work in K2 items. Simon Wells, who has the experimental K2 site at
k2joom.com is looking at this at the moment. I see this as a potential issue from an SEO perspective as all the title tags are h2.
2. I haven't as yet found a way to put articles on the front page and have had to use a traditional Joomla article and publish that to the front page of the site. All the rest on the site mentioned above are K2 items.
3. There seems a tendency to pull item excerpts and publish these to the front page in grid positions. They might look nice, but I'm a firm believer in one page, one function wherever possible. Apart from presenting a visitor with too much choice, there is a very real danger, (in my view), of diluting the SEO value of the major site keywords as a result of this method. I never used to have the front page of Joomla as a blog for this very reason.
4. Probably a templating issue, but you can't have comments on articles in this default template. You have to use the blog template to get the comments working properly that are built into K2. Apparently there is an issue with getting Disqus to work in K2 as well. This is also being looked at by several people at present in the K2 Community.
In summary, I find K2 to be enormously powerful and promises great things compared to what we have been able to do with Joomla in the past. It does require a shift in mindset however from traditonal Joomla development. I'll keep pursuing the learning curve and exploring K2's power.
If you are on Twitter, it's worthwhile following Simon Wells, @k2joom and Hilary Cheyne @hilsatlvsonline for interesting discussions on K2.
Onwards and upwards!
Ric