It's a miracle that Sonic 2 was handed over to a largely western studio with some members of the original japanese Sonic 1 team, and that in spite of the language barrier this imposed, Sonic 2 came out fantastically. Nearly every problem from Sonic 1 is gone.
The speed cap has been removed, the spin dash has been added as a way to quickly gain speed, and the level design is so much more consistently better this time around. No more Labyrinth Zones, every world is as good as the previous one, encouraging the use of speed and momentum to find hidden nooks and crannies, and doing so at higher speeds than before. The pacing has been nailed down to 2 levels per zone, instead of the 3 from before, and now there are more zones and more visual variety to keep things fresh.
There are still some problems. There is at least one zone that for some reason goes back to having 3 levels, and I would say that zone has pacing issues comparable to something like Sonic 1's Spring Yard, where sometimes it's good, and other times it grinds down to a halt, alongside enemy placement that rarely feels fair to predict. The final boss also gives you no rings to protect yourself with, making anything it does a one-hit kill, which is a blatantly cheap way to increase the difficulty.
I would also say the special stages haven't aged well. Technically impressive as they may have been, nowadays they look choppy, and it gets difficult to react to oncoming obstacles. Tails following you around also tends to be a hinderance here, unless you disabled him in the options, which is what I always do. However, the reward for clearing all special stages, Super Sonic, is extremely worth it, and a satisfying victory lap for your effort that I cannot believe recent Sonic games just don't do anymore for anything but scripted sequences.
Sonic 2 has some rough edges towards the end of the game, but for the most part, it's a much more fun experience that everyone should play. I would recommend the version from the Sega Saturn "Sonic Jam" collection (gives you some rings for the final boss to lower the dumb difficulty), or the PC decompilation of the Sonic 2 Android port (widescreen, better special stages, and more), and as a last emergency scenario, the Sonic Origins collection (too expensive, but carries most of the Android benefits...), or the original Genesis version with an infinite lifes cheat code, or save states for the final boss. The good outweighs the bad in this case, and rounds out Sonic 2 as an excellent installment in the franchise.
The speed cap has been removed, the spin dash has been added as a way to quickly gain speed, and the level design is so much more consistently better this time around. No more Labyrinth Zones, every world is as good as the previous one, encouraging the use of speed and momentum to find hidden nooks and crannies, and doing so at higher speeds than before. The pacing has been nailed down to 2 levels per zone, instead of the 3 from before, and now there are more zones and more visual variety to keep things fresh.
There are still some problems. There is at least one zone that for some reason goes back to having 3 levels, and I would say that zone has pacing issues comparable to something like Sonic 1's Spring Yard, where sometimes it's good, and other times it grinds down to a halt, alongside enemy placement that rarely feels fair to predict. The final boss also gives you no rings to protect yourself with, making anything it does a one-hit kill, which is a blatantly cheap way to increase the difficulty.
I would also say the special stages haven't aged well. Technically impressive as they may have been, nowadays they look choppy, and it gets difficult to react to oncoming obstacles. Tails following you around also tends to be a hinderance here, unless you disabled him in the options, which is what I always do. However, the reward for clearing all special stages, Super Sonic, is extremely worth it, and a satisfying victory lap for your effort that I cannot believe recent Sonic games just don't do anymore for anything but scripted sequences.
Sonic 2 has some rough edges towards the end of the game, but for the most part, it's a much more fun experience that everyone should play. I would recommend the version from the Sega Saturn "Sonic Jam" collection (gives you some rings for the final boss to lower the dumb difficulty), or the PC decompilation of the Sonic 2 Android port (widescreen, better special stages, and more), and as a last emergency scenario, the Sonic Origins collection (too expensive, but carries most of the Android benefits...), or the original Genesis version with an infinite lifes cheat code, or save states for the final boss. The good outweighs the bad in this case, and rounds out Sonic 2 as an excellent installment in the franchise.