Liferay Portal Server is a quite good product, I have implemented LR based solutions for several customers now.. It is easy to get into it since you just download a zip file, unpack it and start the server. LR has lots of features, but of course, it can't compete with dedicated products. Wordpress has more blogging features, mediawiki is the far superior wiki, SMF the more powerful forum, ... But: These are all standalone products specialized in being a Blogging platform/Wiki/Forum. The biggest benefit: It's open source. When you use a product, you find things that don't work or work in an unexpected way. But since LR is open source, you can look into the product and find out, how it is done. Themes are very powerful, one can totally change the look of the portal. Using "hooks" alot of the default behavior can be changed. ServiceBuilder allows to add own data to Liferay in a consistent way. With "Application Display Templates" views on items can be scripted without deployment (e.g Image Gallery, flat list, images, carousel, ...) The biggest caveat is documentation. It's getting better, but it is still difficult to find info on lots of things.
User friendly & Quick!