I've played it for a few hours and it's actually pretty good. The "pay now!" element is very much toned down, especially compared to Sonic Jump Rush. I can only recall one point where an offer to spend real money occurred, and that was when I first booted up to tell me about the store. It seems that it limits your daily play, with a gas tank that drains. But it was filling as I played, so I've yet to get an empty tank. I assume it will tell me to "buy gas", but I can't see myself playing for more than 20 minutes a day, so running out of gas doesn't seem to be a big problem.
edit: Watching ads fills the tank back up, but they also offer free refills and the tank takes a while to empty. You'd probably play for 20-30 mins before you'd have to watch a 20 second ad if you want a full tank. Really not that obtrusive, especially compared to Sonic Jump Fever which plays ads all the damn time.
It's not as free roaming like the original, but there is far more control than Sonic Dash and at least the original CT is on iOS if City Rush isn't your thing. No instant deaths when you hit stuff, like Dash. There are four areas that are all connected to create one big city.