Hi. I am looking for a very good WordPress Magazine Theme (for a big portal with news, forum etc.). I do not mid paying some extra $. I had a look at the Arthemia Premium Theme (colorlabsproject.com).

Can you please tell me what you thing about this theme. Is it any good? Before, I was using WooThames.

Do you know any other good Themes that I should consider?

I always prefer making my own. Your own unique theme will distinct your site more from the rest. And WordPress has an excellent themeing system that allows fast and easy deployment of designs as well.

It looks pretty good, though it'll need a lot of content,e?

There are some really really good free magazine style wordpress themes out there. Check out this blog post. This guy has put together a good list. You might want to consider customizing one of these.
http://www.bestwpthemes.com/10-free-wordpress-themes-that-blow-many-premium-themes-away/