The latest releases of liferay has been really feature rich and seen a increasing demand in liferay developers in recent past. Managing multiple websites using single liferay server installation is one of the main reason of liferay gaining popularity.
Liferay jobs are really high paying jobs due to being specialized in portlet segment of java web application development. There are many other portals available with free and paid options. To be highly valuable developer you must focus your knowledge to the JSR way of portlet development, this will ensure you can do development on any other JSR comliant portal as well.
Another positive aspect of Liferay portlet development is "The Liferay marketplace", this can give you an opportunity to develop and sell your own portlet to big businesses and grow your own business.
I have worked on liferay for more than 5 years and found that following interview questions are must know before getting a decent liferay developer job.