The first Sonic was pretty horrible, the second one is just more of the same. It's a misguided mix of bad US CG animation, superhero nonsense, and a comedy that feels like it was written for Ryan Reynolds (but I guess he didn't have time for this). But hey, it's clearly making money, so I wouldn't be surprised if more films followed.
Sonic believes he's a true superhero, but his actions mess up the otherwise so quiet city. Meanwhile, Dr. Robotnik has found a way to return to Earth, and he's bringing a new villain with him. Together they seek out Sonic, hoping to get rid of the pesky little blue hero once and for all.
The animation is ugly, the comedy is truly cringeworthy, and two hours for a very simple plot like this is indefensible. I wish Japan would just handle these game adaptations themselves, on the other hand, this way it's earning them way more money, so let's just hope they're going to spend it on other things worth watching (or playing).