Here's one. I have a head to head "benchmark" involving generating a React web app to display a Gantt chart, add tasks, layer overlaps, read and write to files, etc. I compared implementing this application using both Claude Code with Opus 4.1 / Sonnet 4 (scenario 1) and Claude Code 2 with Sonnet 4.5 (scenario 2) head to head.
The scenario 1 setup could complete the application but it had about 3 major and 3 minor implementation problems. Four of those were easily fixed by pointing them out, but two required significant back and forth with the model to resolve.
The scenario 2 setup completed the application and there were four minor issues, all of which were resolved with one or two corrective prompts.
Toy program, single run through, common cases, stochastic parrot, yadda yadda, but the difference was noticeable in this direct comparison and in other work I've done with the model I see a similar improvement.
Take from that what you will.
The scenario 1 setup could complete the application but it had about 3 major and 3 minor implementation problems. Four of those were easily fixed by pointing them out, but two required significant back and forth with the model to resolve.
The scenario 2 setup completed the application and there were four minor issues, all of which were resolved with one or two corrective prompts.
Toy program, single run through, common cases, stochastic parrot, yadda yadda, but the difference was noticeable in this direct comparison and in other work I've done with the model I see a similar improvement.
Take from that what you will.