It's slow and stupid. It does not do proper research. It does not follow instructions. It randomly decides to stop being agentic, and instead just dumps the code for me to paste. It has the extremely annoying habit of just doing stuff without understanding what I meant, making a mess, then claiming everything is fine. The outdated training data is extremely annoying when working with Nuxt 4+. It is not creative at solving problems. It dosent show the thinking. The Undo code does not give proper feedback on the diff and if it actually did "undo." And I hate the personality. It HAS to be better than it comes off for me because I am actually in a bad mood after having worked with it. I would rather YOLO code with Gemini 3 flash, since it's actually smarter in my assessment, and at least I can iterate faster, and it feels like it has better common sense.
Just as an example, I found an old, terrible app I made years ago for our firm that handles room reservations. I told it to update from Bootstrap to Flowbite UI. Codex just took forever to make a mess, installed version 2.7 when 4.0.1 is the latest, even when I explicitly stated that it should use the absolute latest version. Then it tried to install it and failed, so it reverted to the outdated CDN.
I gave the same task to Claude Code. Same prompt. It one-shotted it quickly. Then I asked it to swap out ALL the fetch logic to have SPA-like functionality with the new beta 4 version of HTMX, and it one-shot that too in the time Codex spent just trying to read a few files in the project.
This reminds me of the feeling I had when I got the Nokia N800. It was so promising on paper, but the product was so bad and terrible to use that I knew Nokia was done for. If this was their take on what an acceptable smartphone could be, it proves that the whole foundation is doomed. If this is OpenAI's take on what an agentic coding assistant should be—something that can run by itself and iterate until it completes its task in an intelligent and creative way.... OpenAI is doomed.
For people suggesting it’s a skill issue: I’ve been using Claude Code for the past 6 months and I genuinely want to make Codex work - it was highly recommended by peers and friends. I’ve tried different model settings, explicitly instructed it to plan first and only execute after my approval, tested it on both Python and TypeScript backend codebases. Results are consistently underwhelming compared to Claude Code.
Claude Code just works for me out of the box. My default workflow is plan mode - a few iterations to nail the approach, then Claude one-shots the implementation after I approve. Haven’t been able to replicate anything close to that with Codex
You are correct in that this mode isn't "out of the box" as it is with Claude (but I don't use it in Claude either).
My preference is to have smart models generate a plan with provided source. I wrote (with AI) a simple python tool that'll filter a codebase and let me select all files or just a subset. I then attach that as context and have a smart model with large context (usually Opus, GPT-5.2, and Gemini 3 Pro in parallel), give me their version of a plan. I then take the best parts of each plan, slap it into a single markdown and have Codex execute in a phased manner. I usually specify that the plan should be phased.
I prefer out-of-CLI planning because frankly it doesn't matter how good Codex or Claude Code dive in, they always miss something unless they read every single file and config. And if they do that, they tip over. Doing it out of band with specialized tools, I can ensure they give me a high quality plan that aligns with the code and expectations, in a single shot (much faster).
Then Claude/Codex/Gemini implement the phased plan - either all at once - or stepwise with me testing the app at each stage.
But yeah, it's not a skill issue on your part if you're used to Plan -> Implement within Claude Code. The Experimental /collab feature does this but it's not supported and more experimental than even the experimental settings.