So, once you reach Top Speed, you will start encountering unavoidable obstacles, including:
Walls of spike balls from the ground below to the top of the screen
Clusters of unavoidable spikes when following the regular path, taking springboards, going through hoops, etc.
Diagonal walls of unavoidable missiles
They've essentially made it so that it's virtually impossible to continue a score run even if you play flawlessly. Not only are many of the features of this update just plain greedy, but they've literally made it impossible for you to progress past a certain point.
This game pretty much demonstrates the series in general - Sonic itself keeps on changing constantly even though the original form was fine before. That's not to say that change in and of itself is a bad thing. Some changes can have a great, positive effect on a series and a game. But changing something that was fine in its inception and making it worse and worse with time and greed is something only the developers seem to have mastered.
Good game design.