A visual masterpiece and gripping storytelling - mostly. Some scenes are so drawn out that they became yawn-inducing - and I like slow paced films, so that's saying something.
You see Ripley from the outside, and it's an excellent rendition of Ripley. Appropriately enigmatic. You'll struggle to understand what goes on inside his head, what's his motivation, at what point does he start making plans, etc. But... this is in fact too enigmatic, and after watching the pivotal murder I was scratching my head so hard, trying to understand his motivation, that I had to go read a paragraph of the original novel, which made everything click into place.
So, sorry, but a film adaptation that has the viewer turn to the source material to understand something is an adaptation that has failed in a fundamental level. This is because Ripley really is enigmatic. Looking at him from the outside is really strange, in a good way. But it's only half, the outside half, of what Highsmith gave us. We are missing the inside half, more of his thought process.
I am all for "give the viewer the clues to figure it out", but in this case it detracts from the experience for no good reason. So, as much as a masterpiece it is on technical levels, and acting, it completely fails as an adaptation. Again, the adaptation sent me to the source material fpr clarification. That's a fail.