I used to do ok on thembefore they dropped the returns. I had nearly the maximum amount and was getting around a 3-4% return which is tax free, worth more to you if you are a 40% tax payer which I'm not, and the potential for a big win and being more fun than an ISA kept me there.
Now I've dropped down to a third of what I had. Partly because I used the money on a conservatory, but the rest will probably be moved too as they have slashed the prize fund.
I think they have never been as good since they introduced the £1M prizes to compete with the lottery. I think they could have sustained more interest by keeping a lot more smaller prizes.