Turkish is indeed often very good. Sometimes, excellent. Biggest airline in the world by some measures, and one that clearly is trying very, very hard to please customers. They are certainly worth a look.
IME, as long as things are going smoothly, Turkish is a good (maybe great) choice for getting to/from places around the eastern end of Europe and beyond. However, if things go sideways and you need helping fixing something, Turkish can leave you going in circles, hitting "sorry, not my department"-style responses, leading to shrugs and a circle of finger-pointing, with you left twisting in the wind. As long as things go as expected, it can be awesome. I had a mix of great and abysmal customer service from Turkish when I was in Istanbul. They did come through for me in the end, but my expectations have been tempered a bit. OTOH, I have experienced estimated phone hold times up to 20 hours(!) with American Airlines in recent months (and sat through 4+ hours listening to their hold music once) so I probably need to cut Turkish more slack.
Their business class is good or great, depending on the aircraft type (older business class cabin, which I prefer, is showing some age, but there is so much leg room you can get up in your seat and jog back and forth - really; newer business class seat is beautiful and sleek, but foot-room is a bit cramped). Their service in business class is over-the-top: includes not one but TWO on-board chefs, quite an impressive spread of decent food, charming little touches like individual candles (electric) on your dinner tray, and more. Their business class lounge in IST is huge, filed with all sorts of free goodies, and is like a vacation destination in itself (my wife groused that we only had a couple to spend there). If you have a business class ticket on TK and a long layover in IST, they offer a FREE hotel night or a free guided city tour, your choice (some conditions apply, and I don't know how these options may have evolved with COVID, but it's a pretty generous benefit). Turkish is viewed by some as "the fourth Middle East premium airline" (Emirates, Qatar, Ethiad being the three that most people see as crazy over-the-top, if you are in a premium class).
Turkish already has a surprisingly extensive network in North America, with nonstop flights to: Atlanta, Boston, Chicago, Dallas, Houston, Los Angeles, Miami, New York, Newark, San Francisco, and DC, plus Montreal, Toronto and Vancouver.
And, -- in The Best Travel News I Read In 2021 That Wasn't About a Vaccine -- Turkish has announced it will begin nonstop flights between Istanbul and SEATTLE in Spring 2022 (they are also adding Detroit). SEA-IST flights are supposed to begin March 9, but they have not been loaded into the system yet (not bookable), and there's no word on frequency or other details (likely a 787-9, which is what they use to Vancouver), so right now it's just an announcement without a lot of details to back it up, and as we know things do change in the age of pandemics. Still, for those of us up in Rickland, this will be an awesome new option to the far end of Europe and beyond, once it starts up. I'll be watching this one closely.