Any of it I've touched, just fell apart like mush.
If it's falling apart when you touch it, it's not what people refer to as string algae. String algae is exactly what it sounds like - stringy. It's tough stuff.
And I think many people don't mind a bit of string algae - or algae of any kind for that matter - but it can take over a pond and that's when it becomes a nuisance. What people need to do though is ask themselves why it's there in such abundance. Something is out of balance. Fix the cause and the algae will be manageable.