Highlights include villain epic archetypes, powerset proliferation, a new zone, and many quality of life improvements. They are also starting to sell extra character slots, and you get two free for “a while.” I had to re-subscribe for the anniversary badge, because I am weak.
The amount of new content is limited, but there are many ways to re-experience the old content. We were having fun tonight with a team of Fire Scrappers and Plant Controllers. If you want a free trial or welcome back code (15 free days with purchase of a month, must have been gone for 90), mention it in the comments and I will send it to the e-mail address you list.
Full disclosure: if I send you a code and you spend money, I get some free time. If you have a friend who plays, have him send you a code and he will get the free time.