I'm intersted in the game, but never played ARPGs before

I never played ARPG before (Diablos and such) but recently I got interested to try. After some googling I found that many recommend Last Epoch. But I'm not sure about some things, and I can't find clear answers online.

1. I'm looking for a singleplayer experience, I'm not really into PvP / Co-op. Is the game playable/beatable in singleplayer?
2. The reviews on Steam are a bit low, is there any real reason for it or is that just some brigading?
3. There are in-game for sale and that kind of puts me off. I don't like microtransactions (and frankly I don't have the money for it), I'm worried the game would press me into buying these like mobile games do. How does it work?

Edit: Thank you for the quick answers! I think I'll be grabing the game soon.