I really liked seneca! It's especially good for sciences in my opinion. I got 3 9s in my sciences revising on seneca, double checking i had everything i needed to know with the CGP textbook, and doing a few past papers. It gives you an excellent overview of everything and is pretty much comprehensive to the spec - it was definitely my main revision source for science. It's also good for going over everything the night before as a refresher as it's pretty quick to get through (not that that is necessarily the best way to revise - i found it helpful though). I used it a little for History but it is definitely too brief to use alone - revision guides were better for me, but seneca helps you understand the broader key points and remember dates. I don't recommend it for English Lit if you are aiming for the top grades - it doesn't really encourage independent thought about the text and if you use it alone you'll be going into the exam with the exact same quotes and points as everyone else who used Seneca. It might be helpful for an overview, but I personally didn't see much use in it for Lit. I used it a bit for maths too, but practice papers are much better for maths revision imo.