Sonnet 4.6 ClaudeCode First Impressions vs. GPT5.5 Codex
Coming from GPT-5.5 Codex.
I've been making an app for roughly 25 hours now with AI, trying to vibe code everything. This obviously has its ups and downs, but so far it's a steady trajectory. As the project gets more complex, it often feels like the polishing stage is just further increasing in size, but I still feel like regardless I could finish this app without coding once myself - which for AI is super impressive, and is making me believe that the future of open source free apps is looking better and better.
I haven't tried Opus 4.7 yet, as I wanted to see what I could do with the base model. Claude told me Sonnet 4.6 was good enough for my code base, so I trusted in it. While it did quite a lot for the 1h 58m 42s session I got out of it, the execution was lacklustre.
It would implement what I said, but aesthetically it wouldn't look great. Even screwing up the alignment/evenness or forgetting basic UI elements I strictly told it to include. When reviewing what it worked on and trying to fix mistakes, it took upwards of 7 attempts to get what I wanted, and sometimes it would progressively make the problem worse.
Sonnet 4.6 might be good for the very bare bones getting a feature to exist, but getting it to look great, perform good, animate well, and integrate alongside other UI elements - it simply cannot do this well enough for me to recommend it whatsoever. Even with the nearly double amount of usage I got out of it compared to GPT-5.5, the consistency and polish of GPT5.5 was a lot better overall, getting the same tasks done in 2 prompts with greater presentation vs. 7+ prompts or being unable to fulfil my task with Sonnet 4.6.
Now this isn't to say GPT5.5 is without issues, as I've had to direct it a lot more than I'd like. It can't really do enough thinking for itself and will usually miss very obvious things I'd want, but with enough prompts and time it can get to where I want my app to be, while I can't say Sonnet 4.6 was good enough to get my project in a state I'd want to release to the public.
Stats:
I used 10% of my total 'All Models' weekly usage for Claude within 1h 58m 42s.
I used 16% of my weekly Codex usage (not all usage) for ChatGPT in a total of 1h 7m, but each execution of a task was done better and to a more finished state, and was needed to go over Sonnet 4.6's work for a more finished product overall.
Going to try Opus 4.7 with ClaudeCode next to see how it compares. Just wanted to let you know that Pro plan is not good enough for vibe coded development using Sonnet 4.6. My app is quite basic all things considered, so expect worse results making games.