I've been using Nitro about 4 years ago for the first time and a few months ago I dug out my old account, deposited and started playing again. Deposits went smoothly, all funds showed up after 15-30min (depends on the fees)- just gotta make sure to have the right cashier BTC address (@the people complaining funds don't show up lol) - I've made plenty BTC off their site and withdrew without an issue - BTC usually on my wallet within an hour if they don't review my transaction (happens on RNG basis, then it takes up to 12h or something but not unbearably long). You do not have to verify yourself at all which is the point of btc so that's good as well, and my account despite milking them big time never got locked or anything - but I've never created multiple ones to abuse their limits so maybe don't do that :) Their odds are decent, you can find better but also worse, sometimes they are super wild and sometimes bugged (1,3 odds ML for both parties lol), at least from what I've seen on the Esport market, which is where I mainly bet. Bets sometimes close too early and their live coverage is barely existant, but they can be bothered to cover pretty low tier games which other bookies just ignore - so that's good. Their limits all the way from high tier to trash tier games are actually decent, nothing for highrollers ofc but 0,016mBTC for some romanian esports league counter strike game starting in 3 days is not too shabby IMO, limits will also rise closer to start. Grading can take 15min to 1hour so it's not the quickest but it's reliable - might annoy the people that want to use their winnings on a game starting right after the previous. Overall coverage has it's ups and downs and the professional bettor won't be able to bet JUST here and have a fantastic time, however it might be a decent addition to ones bookmaker portfolio and most importantly is LEGIT, deposits withdrawals everything works smoothy and their support replies rather quick as well. Can recommend - and I assume these negative reviews are mostly FAKE - especially the ones linking other sites which I assume are the REAL SCAM - stay far away and make sure to report so no poor soul loses their btc to this abuse of trustpilot.
EDIT: a week or so ago they have, after many years, changed the layout and oddsprovider of their sportsbook entirely. IT'S INSANELY BUGGED NOW, but I am not taking this into account, since I expect it to be fixed soon. But the update made the site worse for me (not necessarily for everyone) - it lost it's unique style and their new oddsprovider (ultra) has joke limits. Games are not removed too early & livebetting as well as faster grading is a thing now, unfortunately this does not make up for the baby limits on non mainstream markets where before there was a 13mBTC minimum on the lowest games. Hence I left the site, but low bankroll bettors might still like it here when they get their bugs sorted.
edit2: looks like they got their act together after switching oddsprovider. Limits are reasonable ALMOST everywhere and pretty fkn good in higher tier, laggyness has more or less stopped so best crypto only site out there with no doubt!
edit3: they started limiting their customers though, ultraplay oddsprovider thing, that makes em not the best cryptobook anymore, id put em on same lvl as some others ive reviewed now