If you're after honest opinions... I've got leased solar PV so I can't make any use of export and I use WW in probably the most basic way: the predictive off-peak charging based on solar forecast. I'm a happy user and think the product is great, but it would honestly have to be very cheap for me to continue with a paid subscription 😬
It's not at all because I have any sort of issue with the product or the service (in fact I have recommended it to a few people), it's just simple economics that it probably doesn't actually have the ability to save me much money in my personal situation.
I would personally simply manually set the battery charge level to 100% over winter, and 0% over summer, which are of course the most extreme periods for saving money. And I might simply gamble with 50% over spring and autumn. Nowhere near as elegant as WW of course, and it would be completely wrong on some days sure, but it gets me most of the way there. Even on days where this calculation was totally ineffective I don't see it wasting enough money that a monthly subscription to something makes much sense. If you see what I'm getting at.
Perhaps I'm just not actually the target audience since I would know how and why to set the charge target myself. As much as I enjoy the ease of WW, this part of the solar stuff is purely financially driven for me since I am creating the green energy for me or my neighbours no matter what.
Basically I think I agree with @perfrank that there should be tiers of some sort if possible. I understand the hesitation to complicate the service with different options though