Hi Janet,
I joined HSA about 2 years ago and I find it excellent. I've cover for my wife and 3 kids - works out at €20 every 2 weeks.
I got glasses for my wife and I last year and the refund I got from HSA came close to covering my annual contribution.
The only issue that I have with HSA (and it's a small one) is that you can only submit 3 claims at one time, so you need to keep on top of your receipts as you get them. It takes approximately 2 weeks to get your cheque from them.
I'm also in BUPA and am just about to submit my claims for '04.