I do not think this is a great movie

Yeah I kind of agree. The plot is essentially "old man sees his friend's lonely old daughter, he decides to marry his daughter to avoid that, he marries off his daughter". There's really no conflict or climax or traditional plot structure in the movie at all.

But I still kind of liked the movie. I like the way the Technicolor looks and the movie had a very slow pace, so it was kind of relaxing to watch.

If that's your take on it, I doubt you'll find much interest in Ozu's other films. He doesn't have conventional plot in the sense you speak of. I feel that it was a natural movie, taking on real life characters and themes. But, personal taste I suppose

Ozu's stories are very Japanese and I don't think he made them with export in mind. A lot of Westerners won't "get" everything in his films just because of the cultural context. I'm not saying it's some inscrutable "mystical Japanese" thing that can't be understood by "alien Westerners", either; just that you have to be somewhat familiar with the context in which his movies are made to get them. All of his movies have certain themes in them, many relating to family relationships and the conflict between tradition and modernity. It sounds like you were watching this film without the context in mind, expecting just a generic timeless story with no wider point in mind. So it's not surprising you didn't like it much.

Too clean? Who is the decider on that?

Ozu was a master or cinema and his movies were indeed very profound.

It's about what happens when a man loses his wife early and has a daughter who is helping him get through life. She could continue to do that her whole life, but as the example of "the Gourd" showed, it might mean that she would become bitter and resentful. It would be much better for her to marry and start her own life, but the pain for her father will be immense. Yet little of this emotion is shown. We must intuit what is going on in these interior monologs.