Everything I have ever wanted in a fighting game except for my character being a low tier. I honestly cannot believe SF6 released in so good of a state. World Tour is genuinely a pretty great single player mode and I'm so excited for what it means for the future of big budget fighters.
As for the actual head to head fighting, it's probably the best the series has ever had on launch. My favorite game in the series mechanically is definitely still 3rd Strike, but SF6 comes pretty close, and that's with no patches to balance things out. The drive system is excellent through and through, it almost feels weird to play Street Fighter without drive rush, it just adds so much depth to the game. Parrying is a really well thought out mechanic and I'm so surprised it isn't incredibly busted. Drive management makes SF6 a genuinely really difficult game at a higher level, it's fantastic.
The only real problem I have with the game is the roster which is a shame. The launch roster is 18 characters which is perfectly acceptable, but 10 of them are from Street Fighter 2. There isn't a single character from SF3, Alpha, or 5 if you don't include Luke. I really like what they did with the returning characters in both design and gameplay, but it's a shame there isn't more variety, because the newcomers are really great.
Overall, a great visual identity, excellent character balance, well though out mechanical balance, a near perfect online experience, and genuinely good single player and casual content make SF6 one of the best fighting games I've ever played.