It'll be tough for you to find a middle of the road review of this, because people either pay a monthly subscription fee, and are aware of this, and use it because otherwise they'd be wasting their money... or they don't use, it and can't really contribute.

Personally, I've been turned off by it for a couple reasons:

• I do not agree with their manifesto, which flies in the face of privacy and the dangers of the Filter Bubble

  And when you ask your own AI a question like "does God exist?" it will answer it relying on biases you preconfigured. When you ask it to recommend a good restaurant nearby, it will do so knowing what kind of food you like to eat. The same will happen when you ask it to recommend a good coffee maker - it will know the brands you like, your likely budget and the kind of coffee you usually drink. All this information will be volunteered to the AI by you...

• The face of the company is rather weird
• Subscription money goes to AI
• It doesn't offer me sufficient value compared to free search engines that keep me anonymous by default.

ETA: If you use Kagi, don't rely on promises alone to keep your data private. Consider a masked email for login (you must provide one), and definitely use their Privacy Pass to keep your searches unlinked from your account instead.