No, ignore people who say that.
They are a step up from GCSE, but as soon as you get your head around that it will be fine. If you work hard, then you will do well. All B's at GCSE doesn't suck either. I know people who would have been more than happy to get those results. But use the fact that you were disappointed as an incentive to do even better next year.
4 AS levels should be fine, but the key to A-levels is good planning and organization.
At A-level it is important to read around the subject and do extra work/research without being told to all the time, so make sure you are passionate about (or at least interested) in the subjects you are doing, because then you will be more inclined to work.
Good luck!