A good thing with valued opinions is when you are emailed to take part in a survey they tell you how long it will take and your reward. Unlike other companies they pay you in cash and this can vary between 25p to £4 per survey. Surveys range from 2 minutes to an hour. You have to accumulate £10 before you can redeem the cash but there are many vouchers you can chose from including donating the money to charity. I get surveys every couple of days and it usually takes between 4 - 8 weeks to earn the £10. Delivery comes really quickly.
My only negative is sometimes there are qualification questions to see if you are the age / gender / location of the group they want to get the opinions off. Occasionally you can spend several minutes answering questions and giving your opinions only to find out that you didnt qualify and some of the surveys are too long for the reward you get, but the times they estimate in the emails are accurate so you dont have to enter the survey.