I like all of the things you can do with LiNK, especially looking at previous editions of the NEC, plus looking at other codes and standards that I rarely use, but sometimes need to read. The search function is very good, and you can even search topics in multiple codes and standards at the same time. It has the ability to bookmark and you can click and view the previous code language when trying to understand what change was actually made. They also have put a lot of the handbook commentary in the code, and click on "enhanced content" to view that. I don't think it has everything the handbook would, but it has a lot of "enhanced content".
As far as it being worth it, it is the only choice for an electronic version, but only you can decide its worth.