Early user testing suggests OpenAI’s newly released GPT-5 represents a sharper break from GPT-4 than previous model upgrades, with developers citing markedly stronger reasoning, automatic tool-calling and a 400,000-token context window—50 times larger than the 8,000 tokens offered by GPT-4. Side-by-side demonstrations show the difference in applied capability: when asked to “create a single-page HTML fruit-machine simulation,” GPT-4 (dated June 2023) produced a rudimentary spreadsheet-style page, whereas GPT-5 (August 2025) generated a full, interactive game complete with animations and tilt detection in a single pass. OpenAI is routing most requests through an adaptive model selector but offers paying customers direct access to a high-end "GPT-5 Thinking" tier, which spends more time on multi-step reasoning. Early feedback indicates the model rewards precise prompting; users report higher quality responses when they explicitly ask it to “think hard.” The rapid jump has surprised some observers amid an increasingly crowded release cycle, yet analysts note that the gains in context length and autonomous problem-solving could open new enterprise uses from large-document analysis to automated software prototyping.