I have been on it twice. First time 2019 through to early 2021.
Prices were low, particularly during the first lockdown. Quite a few negative pricing events. My average monthly price was 5-12 p/kWh.
Starting last year, prices crept up more and more as the wholesale price rose so I switched tariffs.
Back to this summer, in August I signed back up for Agile. Not because it is currently cheaper but because it had a cap of 55p/kWh for 12 months. That was comparable to October's then forecasted rates, and lower than January/April's. I did it on the basis of being at the cap most of the time, with anything lower a bonus.
10 days ago, Octopus increased the cap for new users to 78p so the benfit is now not as clear.
The rate for the next day is published about 4pm. You can view it in your Octopus account page or here (select your correct region)
https://www.energy-stats.uk/octopus-agi ... n-england/
You'll need a suitable smart meter (some SMETS1 meters don't work with Octopus).
If I had an EV or battery storage, the Go tariff would have been a better deal.