Claude 4 Sonnet: My First-Week Assessment for Enterprise Use

Anthropic released Claude 4 Sonnet this week. It's the newest flagship general-purpose model. After a week of testing on professional services workflows, here's my assessment.

The Capability Leap

Claude 4 Sonnet is a meaningful step up from Claude 3.7 Sonnet. The improvements are visible across multiple dimensions:

Reasoning. Harder problems that required extended thinking are now handled well by standard inference. Throughput is higher.

Hallucination Reduction. Fewer confident-but-wrong answers. Better self-correction. More reliable.

Long Context Understanding. Handling longer documents (100K+ tokens) is now faster and more accurate.

Code Generation. Better at writing complex, working code. Integration-level quality.

Real-World Performance

I tested Claude 4 Sonnet on actual professional services workflows:

Contract Analysis: 95%+ accuracy on identifying risks, missing clauses, problematic terms. Better than 3.7 by about 5-8%.

Legal Research: Synthesizing complex multi-case research is more accurate. Fewer gaps in reasoning.

Document Drafting: Initial drafts are closer to final quality. Fewer rounds of revision needed.

The Pricing Question

Claude 4 Sonnet costs roughly the same as Claude 3.7 Sonnet. This is important: you get better capability at the same price. Or you get the same results at lower cost if you can use a cheaper, smaller model.

For most professional services workflows, Claude 4 Sonnet replaces Claude 3.7 Sonnet. It's a straight upgrade.

When to Upgrade

If you're currently using Claude 3.7 Sonnet:

Upgrade immediately if: You're doing complex analysis (contract review, risk assessment, multi-case synthesis). The quality improvements are material.

Wait if: You're doing simple tasks (summarization, classification, basic writing). The improvements don't justify retesting and redeployment.

Consider a hybrid if: Route hard problems to Claude 4, simple problems to 3.7 (cheaper). Your costs might stay the same while quality improves on hard problems.

Comparison to Competitors

vs. GPT-4o: Claude 4 is now ahead on most professional services tasks. Better reasoning, fewer hallucinations. GPT-4o will push back (OpenAI will iterate), but Claude 4 currently leads.

vs. GPT-4.5: Too close to call. Both are strong. Specific task performance varies. Test on your work.

vs. Grok 3: Claude 4 is more reliable. Grok is cheaper. For professional services, reliability wins.

The Deployment Recommendation

For professional services firms currently on Claude 3.7 or earlier:

1. Upgrade your high-value workflows to Claude 4 Sonnet
2. Keep simpler tasks on cheaper models (Haiku, 3.5 Sonnet)
3. Test the new models on a sample of actual work
4. Measure quality improvements vs. cost changes

Don't rip-and-replace everything. Be methodical.

Looking Ahead

Claude 4 Sonnet is probably the strongest general-purpose model for professional services work as of May 2025. By August, there will probably be competitive responses from OpenAI or Google. Competition will continue to intensify.

Choose Claude 4 now if it solves your problems. But know that better options might emerge in 6 months. Stay flexible.