You have had other great answers. I will add my two Tomarani cents. I have not played with the rental gameplay yet and I have not run into the save corruption bug or issue at all yet. I play generally in other worlds but I have sent a few households to visit Tomarang and that was fine. The most I ran into was a buggy walk when a mother carried a toddler through the town but that corrected itself. I played with a normal residential lot with no issues. Sometime fairly soon, I will play the Bun Ma household in their normal residence. The CAS/BB in the game is all working fine. I am waiting on the patches to get into rental building and landlord/tenant gameplay. Playing mainly in other worlds right now, my main game save is fine.
Yes, it's always a great suggestion to back things up frequently as much as possible. That is a helpful reminder.
There isn't a need to be afraid of using Tomarang itself. I would probably test out rental gameplay and switching a lot from a residential rental to a residential lot in a separate save while they are working on that if that is something that you want to do. It's such a known bug that I'm sure they are working on it. I'm looking forward to the new patch. I have the holiday bug which they are fixing so I am appreciative of that repair.
Personally, I think Tomarang is an interesting world that adds to the game. There are no other worlds exactly like it. I honestly enjoy the night markets and the different settings around the world. I find it replayable even as a tourist destination. I don't have a problem with it being a bit different from other worlds. It is actually a fun place to send families to travel because of the hopscotch in the park, the tiger sanctuary and the non-alcoholic drinks that children can order. The botanical garden is really nice and there are monuments to photograph, so tourists can keep busy. My households that visited there are better because of having gone in my opinion. I think Tomarang can be fun and I am glad that it was added.
