Hi everyone: This is my first post here, and I felt I just had to share my experience. I have always been a huge fan of ChatGPT. It has solved many complex issues for me that other models, like Claude Opus, couldn’t handle 3 months ago.
A while ago, I was using an older version (either GPT-5.3 or 5.4) with the “extended thinking” feature turned on. I used it to fine-tune a complex algorithm for my side project. It took almost 50 minutes to generate an answer, but the response was incredibly thorough and detailed. When GPT-5.5 came out, I was thrilled at first because it generated the response in just 10 minutes with extended thinking. However, after using it consistently for a month, I have completely given up on it.
While GPT-5.5 is fast, it fails at complex problem-solving. When it gets stuck, it just loops back and forth repeating the same mistakes without actually fixing the issue. For serious developers handling advanced architecture, I feel GPT-5.5 is regular and not worth recommending.
Just yesterday, after spending four frustrating days trying to figure out the algorithm with GPT-5.5, I decided to try Fable 5. Using the exact same prompt, Fable 5 absolutely destroyed GPT-5.5’s analysis. It immediately identified the root issue and provided the exact architectural fine-tuning needed to solve the problem.
Fable 5 is doing an amazing job right now. Moving forward, I am switching my workflow. For tasks where I still want to use ChatGPT, I am going back to GPT-5.4. I am perfectly fine waiting 50 minutes for a response if it means getting the deep, accurate problem-solving I need to fix complex developer issues.