What's up bro! You're going to love Anni. There's so much new content it's like a couple more expansions were added to D2. It's all integrated nicely and feels like official content for the most part.

Definitely check out the wiki so you can get an idea of what Anni has to offer. Since you haven't played in awhile, starting off may seem a little tough at first but it gets easier as you move forward. Monsters are stronger than normal but all Rare/Set/Unique items are buffed so it balances out.

I highly recommend being online when the reset happens (yet to be announced). The first public game up will be fun and hilarious. There will probably be around 20+ players in one game smashing demon face while we race to Hell.

Welcome and have fun!