https://blog.google/technology/ai/google-gemini-next-generation-model-february-2024/

Our teams continue pushing the frontiers of our latest models with safety at the core. They are making rapid progress. In fact, we’re ready to introduce the next generation: Gemini 1.5. It shows dramatic improvements across a number of dimensions and 1.5 Pro achieves comparable quality to 1.0 Ultra, while using less compute.

Once both have been publically available for long enough to get users, I'll resolve this to whether or not I think it's roughly as good as Ultra or noiceably worse for generic LLM use cases.