The thing about this type of game is that there is very delicate balance to be struck between offering the right level of challenge and frustrating the player to the point where they quit. This is made all the more difficult by the range of player abilities in both puzzle solving and precision jumping. However there are plenty things a developer can do to make things better or to make things worse. The position of checkpoints is huge. Never put a tricky challenge at the end of a long boring section. Good visual clues are also ideal so that the player always know what they are supposed to go even if it is not obvious how they are going to get there. Inside get s the balance very right in my opinion. I had to replay many sections more than once but I never felt really lost and I never felt like quitting in frustration. Several sections seemed impossible at first but there were always subtle clues to point the way and none of the jumps required nano-precision. If you can interact with an object in the game then you can be pretty sure you will need it to solve a puzzle which is very re-assuring.
A story about my uncle on the other hand is a lot more frustrating. It is often not clear which way you need to go (including several sections in dark caves where you cannot actually see). The checkpoints are often cruel requiring the player to repeat long boring sections over and over just to fail at the same difficult bit. The game is to be praised for having some wonderful movement abilities including a grapple and rocket boots but some of the jumping is just to hard for me requiring multiple attempts before I can get the timing right. I am currently in a section called the ice caves and even though I am pretty close to the end of the game I am thinking of abandoning it because a particular challenge with falling blocks I have to jump between has beaten me at least ten times. This is not the first such roadblock I have encountered and these hurdles do diminish the overall enjoyment of the game for me. If I try a challenge three or four times and then succeed I feel a sense of triumph and elation. On the other hand if I have to replay a section twenty times to overcome it then I feel jaded and weary particularly in some sections where it isn't even clear that I am on the right track. The game is still worth playing just to experience the thrill of navigating a beautifully imagined world but don't expect to finish it unless you are very persistent and willing to put up with a good deal of frustration along the way.
I have no such reservations about Inside. The difficult level is very well balanced and it is never cruel to its players. However if you do play the game be prepared for some very dark weirdness. It starts off with a little boy running for his life from nasty men with tranquilliser guns and it rapidly gets blacker and weirder from there. The final section in particular is downright bizarre and I have no idea at all what it is all about.