Valued Opinions is one of the best paid online survey sites I have come across. Sign-up is quite simple, taking me only about 10 minutes, and from then on it is possible to get emails which contain links to the surveys.
These emails are always very clear, they contain a general overview of the survey about to be undertaken and as such include the cash reward, subject area and length of time. The email also contains a link to your own unique survey.
The surveys themselves are generally relatively well phrased and not to repetitive, and the surveys I receive cover a wide range of topics. I generally find that the surveys are slightly shorter than the advised time, but maybe I am just a fast reader!
As for the cash reward this is generally a decent amount. It can range in value from about 50p up to £5, although there are higher values for specific tasks sometime available but as of yet I have been unable to get this. The rate of pay is approximately £5 an hour using the estimations within the email, so that a 30 minute survey will pay out £2.5, although this value varies and as I have already mentioned the time estimates are in my experience slightly longer than it takes to do the survey in reality. Once the amount in the online account reaches £10 it is possible to change this for a voucher. Whilst it may be preferable to have it in cash, for people in the UK there should be a voucher for everyone, as the list is very long and includes household names such as Amazon, Tesco and John Lewis. I have always gone for Tesco vouchers, and whilst the website warns it may take up to 28 days for delivery, in my experience the delivery has always been under a week.
There are a couple of negatives though. When a survey is completed the money is in the account under 'pending' and it can take a month for it to be OK to withdrawal the money. Secondly, it is not uncommon to answer a couple of questions, only to be told that the website is after a certain group of people, and nothing is earned for this. However, I personally find this to be a very minor fault and so would recommend using this website for a little bit of extra cash if there is spare time.