OpenAI’s GPT-5 family has arrived, promising a leap in AI performance for business owners and developers. After 12 hours of rigorous testing against Claude and Gemini, we uncover its strengths, surprising hallucinations, and unbeatable API value.
Introduction to GPT-5
OpenAI’s GPT-5 family, including GPT-5 and GPT-5 Mini, has been released to all users, even those on free ChatGPT plans. This upgrade simplifies the model selection process, offering a default GPT-5 mode for quick responses and a “thinking mode” for complex queries. However, after extensive testing from an online business owner’s perspective, we found that while GPT-5 excels in benchmarks and usability, it still struggles with hallucinations.
Key Insight: GPT-5 automatically switches to reasoning mode for complex questions, eliminating the need to manually select models like GPT-4o or GPT-3.
Key Features of GPT-5
GPT-5 introduces several improvements that make it a game-changer for casual and power users alike:
Simplified Model Selection
No more choosing between multiple models. GPT-5 adapts dynamically, using reasoning mode for complex tasks.
Enhanced Emotional Intelligence
Responses are more emphatic and tailored, with a conversational tone that feels human.
Free Access for All
Even free users get GPT-5, though with a smaller context window and no thinking mode.
Message Limits
80 messages/hour for GPT-5; 200 messages/week for thinking mode. Manage usage carefully.
Note: Free users get basic GPT-5 access, but paid users unlock a larger context window and thinking mode for deeper reasoning.
7 Real-World Test Results
We tested GPT-5, GPT-5 Mini, Claude’s Opus and Sonnet, and Gemini 2.5 Pro across seven business-relevant tasks. Here’s what we found:
Difficult Client Email
GPT-5 crafted a professional, concise email with a balanced tone, avoiding excessive deference. It outperformed Gemini 2.5 Flash (overly verbose), Opus (AI-like tone), and Sonnet (generic). GPT-5 Mini struggled with formatting and AI-isms like excessive em-dashes.
Ad Campaign Analysis
GPT-5 analyzed Meta ad data efficiently, providing clear, data-backed insights (e.g., best creatives, demographics). Gemini 2.5 Pro was verbose and lacked specific numbers, while Opus failed due to token limits.
Vibe Coding (Retirement Planner)
GPT-5 built a visually appealing retirement planner with Monte Carlo simulations, outperforming Gemini 2.5 Pro’s basic, non-functional output. Opus was functional but less polished, with design glitches.
Product Launch Plan
GPT-5 delivered a detailed six-week launch strategy with specific angles (e.g., “last chance + decision cyclist”). Opus and Gemini were less creative, and Sonnet was overly generic.
LinkedIn Post
GPT-5 created a concise, authentic post avoiding “AI bro” clichés. Opus had stronger storytelling but felt AI-written. Gemini 2.5 Pro was competitive but overly formal, and Sonnet underperformed.
Meeting Transcript Analysis
GPT-5 Mini extracted key decisions and action items concisely, outperforming Gemini 2.5 Flash’s verbose output. It also captured more action items (six vs. five).
Hallucination Test
GPT-5 hallucinated in two of five chats, e.g., inventing a nonexistent MCP.json file for integration. A web search later corrected it, but hallucinations remain a concern.
Warning: Despite OpenAI’s claims, GPT-5 still hallucinates frequently. Always verify critical outputs with external sources.
API and Pricing Advantages
GPT-5’s API is a standout for developers. Priced at the same level as Gemini 2.5 Pro but with a 400,000-token context window (vs. Gemini’s 200,000), it’s more cost-effective. GPT-5 Mini is the real game-changer, offering near-GPT-5 performance at five times lower cost than competitors like Claude’s Opus or Sonnet.
GPT-5
$0.30
400,000-token context, outperforms Gemini 2.5 Pro.
GPT-5 Mini
$0.06
~20% less powerful but 5x cheaper than competitors.
Gemini 2.5 Pro
$0.30
200,000-token limit, more expensive post-limit.
Claude Opus
$15
High cost, limited to 200,000 tokens.
Pro Tip: GPT-5 Mini is ideal for automation tasks due to its low cost and strong performance.
Key Takeaways and Next Steps
GPT-5 is a major upgrade for ChatGPT users and developers, offering unmatched intelligence, affordability, and usability. However, its walled-garden approach limits integrations (e.g., no native Gmail or Google Calendar yet), and hallucinations require caution. GPT-5 Mini is the standout for cost-conscious automation.
Strengths
Top-tier benchmarks, intuitive UI, affordable API, strong writing and coding.
WeaknessesDeclarations
Persistent hallucinations, limited integrations compared to Claude.
Best Use Cases
GPT-5 for complex tasks; GPT-5 Mini for cost-effective automation.
Ready to Try GPT-5?
Install ChatGPT to experience GPT-5 for free, or explore the API for powerful automation.
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