Memento was literally a mystery film, and unless you kind of know which context clues to look for you're not really going to figure out what's going on until the end. Inception had a lot of mystery to it in terms of what's real and what's not, but in the end the mysterious portion of it is not really the point of the movie. We're not really presented with the question of what's real as the core mystery to be solved. The fact that Nolan doesn't actually reveal anything at the end aside from the context clues mentioned in the video and in the article posted at the top of the comments and his remarks after that "it doesn't really matter whether or not Cobb is in a dream" lead me to believe a lot of it is more of a character study of that man rather than an overarching sci-fi type world. The journey is not really to decide whether or not Cobb is living in the dream world but more so whether he is at peace either way.
I do agree with your general assertion that Momento is a more coherent film and I think that is largely due to the scope and scale of those respective films' budgets.
I do agree with your general assertion that Momento is a more coherent film and I think that is largely due to the scope and scale of those respective films' budgets.