Orsinium is definitely worth it. It's a huge area with a lot to do. It's at least 3 times the size of DB, both in area and in terms of content. Yes, it is so worth it!

Is Elsweyr worth it?

It's largely worth it. Elsweyr is an enjoyable expansion that's packed with dragons, necromancers, and a fascinating race of cat people. It's brimming with the kind of content that has made The Elder Scrolls Online one of the best MMORPGs around since its overhaul in 2015.

Is it worth subscribing to eso?

The good news is that you don't need ESO Plus to play the game. The bad news is that it's such a huge quality of life improvement that it feels mandatory if you're playing for any extended period of time. There's a free trial which gives you a taste of what the membership has to offer, and many find it hard to go back.