Right now there are 2143 players on Coinpoker, 2058 on PartyPoker and 20562 on Stars. Several hundred of the Coinpoker players look like they are in freerolls, but there's a reasonable spread of micro cash tables. I've only been there a couple of days so can't comment on how well it's playing.
The currency they use (USDT) is tied to the dollar, so 100USDT is $100. If you don't have crypto you'd need to get a DeFi wallet, like Metamask or Coinbase, and then buy from one of the crypto exchanges. I use Revolut as I have an account there already, and it's easy to transfer funds in. But there are lots of options. You might need to buy a small amount of ETH (like $5 or so) to pay any network fees to get it to Coinpoker. I lost about 2-3% in fees and the 5USDT charge from Coinpoker to withdraw is expensive and will deter some.
It's a bit of a hassle to setup but after that it should be straightforward. And it's crypto so the whole thing carries risk, although using USDT reduces some of that.
HUDs aren't allowed although there is one that claims to work but it looks unmaintained and I don't intend trying it. Overall the game is a slick interface and the only pain for me is that you can't download your hand history, although apparently you can request it by email from support.
