I'm sure the game will play wonderfully, and after the E3 footage, I'm much more confident about the visuals and framerate. I expect sounds to be moderately improved, but not on par with the best in the business. The game will likely be criticized for its comparatively small car and track count by people who prioritize content over quality, and after dealing with the ramifications of the flawed mindset over the past six years, I honestly couldn't care less how they feel. So in all of those respects, I'm sure GT Sport will be fine.
However, I believe the eSports slant will only excite a select few, likely the best players in the world (not sure it's the most intelligent strategy to build your game around the top 5% of players on your leaderboards, but perhaps I have it all wrong). Polyphony is calling this a simulator for everyone, but I can't see anyone but the most serious players caring. Unfortunately, those most serious usually spend their time in iRacing and AC, and scoff at Gran Turismo. So I think it'll have a tough time courting the sim faithful.
Which brings me to how I personally feel about GT Sport (which, if I may shamelessly self-promote, I say more eloquently in a post I recently made on my personal blog, which you can reach by the first link in my sig). The things that made GT what it was do not appear to be present in this game. There's no massive single-player campaign, and no way to really upgrade, personalize, or customize your cars (save for the livery editor). It seems to be all about competitive online racing, with no game to complement the simulation. In that way, it'll be much more like the simulators it's trying to steal mindshare from, and less like a GT game in the traditional sense. Unfortunately, since about twelve other games are doing exactly the same thing, I highly doubt it'll stand out in any meaningful way.
TL;DR: Technically great, but ultimately not innovative or compelling enough to draw either the hardcore or casual crowd.