I have a college level background in physics and am reading these to fill in gaps in my knowledge. I have learned many new things already (3/4 of the way through book 1); however I think it is worth stating a few potential issues that haven't been elucidated by other reviews. Ultimately I am happy that I bought the books but I would not recommend them to others without reservation.
First, I do not think these books are suitable for someone who does not already have background in the material. They move very quickly and don't spend enough time on any one topic to properly ingrain it into the mind. If you are trying to teach yourself from scratch, I would recommend a traditional textbook over these lectures. If you do decide to go with these, you will also have to buy a supplement like "Exercises for the Feynman Lectures on Physics" since the book doesn't have any problem sets.
Second, the books are showing their age. There were several points where for example a 3d graph would have made things much clearer, but due to the limitations of the time it wasn't possible to provide such a figure. There was an entire chapter on numerical calculation which is interesting purely in a historical manner now, as it teaches you how calculation was done before the availability of pocket calculators. There were a few points where Feynman stated that something wasn't figured out at the time, and I was left wondering if we had improved our understanding of it in the 50 years since. The fundamental material hasn't changed at all since Feynman gave the lectures, but there are still many small ways in which the age of the books are a detriment.
Finally, I agree with the other comments about difficult to read glossy paper, small print, and poor use of space.