Jason Zook@jasondoesstuff
I've been using Fable 5 and GPT-5.6 Sol A LOT the past few days. Both on effort level high. Three different projects with vastly different codebases.
Some thoughts from real-world use...
1. Fable 5 **never** makes mistakes. Not once. I've given it complex features and it never randomly messes up. It's actually blown my mind a bit.
2. GPT-5.6 Sol gets it right 50% of the time. It hasn't deleted any production code, which is great, but it also makes stupid mistakes and just forgets to do part of a feature entirely. I find myself having to go back and forth with GPT-5.6 just as much as I did with GPT-5.5.
3. I built a Captions feature into our video editing app (SceneRoll) in two separate workspaces, one with Fable 5 and one with GPT-5.6 Sol (same starting prompt). Fable 5's was nearly perfect out of the gate (a couple small UI tweaks). GPT-5.6 Sol didn't even have the captions playable on video 😂. I spent an additional hour and then finally just gave up on GPT.
4. Fable 5 thinks about a lot more edge cases. It's going 4-5 steps further without telling it to even do that.
5. GPT-5.6 Sol does not think very far ahead. Yes, it's better than 5.5, but I wouldn't say noticeably.
6. Fable 5 is a more creative thinker. I asked it build a gamification trial onboarding flow for our content creation app (Solo Content Studio). It was REALLY good. It thought through little animations, details, and even small alerts to give to the user.
7. GPT-5.6 Sol can work within a brand system well, but it does deviate randomly. It LOVES trying to shove a dark mode moment and random shapes into a page. Fable 5 never does this. It just follows the brand system and never invents any random design treatments.
8. I am NOT A DEVELOPER, so take this with a grain of salt: GPT-5.6 Sol writes more code than Fable 5. It seems to just try to do more or write more, when it really doesn't have to. On a feature that's 1,000 lines of code, Fable 5 usually removes 15% of what GPT-5.6 Sol wrote.
9. GPT-5.6 Sol wins by a mile on actual usage. Think of it like a Toyota Prius. It's going to give you 80 MPG and you're never going to need to worry about your usage. Fable 5 is like a (token) gas-guzzling SUV. You feel how much usage it tears through.
10. I used "Ultra" mode on both. I'm not entirely sure I see the point, unless you just want to YOLO your usage and have it work on something big overnight. I would only trust Fable 5 to work overnight in Ultracode. It would nuke usage, so I'd rather just babysit it during the day and get a lot more done with the usage.
11. I have a 13-year old codebase (Teachery) that I've tried to use GPT-5.6 Sol on multiple times, and multiple times it cannot do the simplest of tasks correctly. I don't know if it's just getting lost in the old spaghetti code or what, but it fails to do simple things like take a list of 140 users, only show 15, paginate the rest. Fable 5 accomplished this in 1 sentence and 1 attempt. GPT failed 3 times on this task.
12. Unrelated to code, I feel like Fable 5 and GPT-5.6 Sol are on the same playing field when it comes to brainstorming, analysis of data, and big picture thinking. Neither feels better than the other.
13. Oh, when you give GPT-5.6 Sol a complex task, it will spawn ONE MILLION AGENTS 😅. It's actually kind of insane. I don't care that it does this, but I find that Fable 5 feels more conservative with its agents. It uses them, but it doesn't just whack 20 of them onto tasks.
FINAL THOUGHTS...
The takeaways above, were based on singular use with each model.
My typical building flow is Fable 5 as planner/reviewer, GPT-5.6 as code writer, Fable 5 deploys Opus/Sonnet as agents to verify and test. This is the best way to squeeze the most juice out of both models (and really, just save as much Fable usage as possible).
Like many other people, I'm going to be sad to see Fable 5 goes to usage credits only. My hope is that Opus 5 ends up with all the same reasoning abilities, and can orchestrate and manage big tasks like Fable 5 does.
But, being totally honest, if I have to pay $200-$500 in Fable 5 usage credits a month to continue to use it with sky-high confidence and accuracy, I’ll do it in a heartbeat.
