Nano Banana 2: evaluating Gemini 3.1 Flash Image Preview

The release

Google introduced Nano Banana 2, Gemini 3.1 Flash Image Preview, on February 26, 2026.

Test the workload you intend to move

Group sample requests by job: new product compositions, edits of existing assets, and campaign variations. Keep those categories separate in the results. A model can be a useful default for one job while still needing review for another.

Preserve the same sources and prompts for the first pass. After that baseline, improve instructions specifically for the new model and label those results as a separate experiment.

Record operating behavior

Alongside visual review, record completed requests, elapsed time, and spend. Use enough repetitions to notice variability, but do not turn a single small pilot into a public reliability claim.

For a marketing team, the useful question is how quickly a brief becomes an approved asset. For developers, the useful question is whether request handling and output parsing remain predictable. Your acceptance plan should include both.

Keep preview configuration replaceable

Store model selection centrally and monitor the official release notes. A preview can be a reasonable evaluation target, but applications still need a plan for identifier changes and retirement. Consult current availability before adopting the historical preview ID.