I posted some of my experience with Kagi's LLM features a few months ago here: https://literature.cafe/comment/6674957 . TL;DR: the summarizer and document discussion is fantastic, because it does not hallucinate. The search integration is as good as anyone else's, but still nothing to write home about.

The Kagi assistant isn't new, by the way; I've been using it for almost a year now. It's now out of beta and has an improved UI, but the core functionality seems mostly the same.

As far as actual search goes, I don't find it especially useful. It's better than Bing Chat or whatever they call it now because it hallucinates less, but the core concept still needs work. It basically takes a few search results and feeds them into the LLM for a summary. That's not useless, but it's certainly not a game-changer. I typically want to check its references anyway, so it doesn't really save me time in practice.

Kagi's search is primarily not LLM-based and I still find the results and features to be worth the price, after being increasingly frustrated with Google's decay in recent years. I subscribed to the "Ultimate" Kagi plan specifically because I wanted access to all the premium language models, since subscribing to either ChatGPT or Claude would cost about the same as Kagi, while Kagi gives me access to both (plus Mistral and Gemini). So if you're interested in playing around with the latest premium models, I still think Kagi's Ultimate plan is a good deal.

That said, I've been disappointed with the development of LLMs this year across the board, and I'm not convinced any of them are worth the money at this point. This isn't so much a problem with Kagi as it is with all the LLM vendors. The models have gotten significantly worse for my use cases compared to last year, and I don't quite understand why; I guess they are optimizing for benchmarks that simply don't align with my needs. I had great success getting zsh or Python one-liners last year, for example, whereas now it always seems to give me wrong or incomplete answers.

My biggest piece of advice when dealing with any LLM-based tools, including Kagi's, is: don't use it for anything you're not able to validate and correct on your own. It's just a time-saver, not a substitute for your own skills and knowledge.