I think having the age of consent at 16 on the whole is a good indicator of the level of maturity needed for teenagers to understand the consequences of sex. However, I think it should be used more as an indicator than an absolute. You hear these ridiculous stories of people getting prosecuted for having sex with someone who is almost 16 but not quite, knowing full well that if said person was a couple of weeks older (i.e. had their 16th birthday), the police would not be interested.
Each case should be judged on its merit and the personalities and mental capabilities of the people involved. The law needs to be more flexible.
Having said that, I think the sentences on real offenders should be increased. Also, women should get the same punishment as men who have committed the same crime. Sorry ladies, but abuse by females does exist in society (its a bit taboo at the moment), and it is daft and grossly unfair that a female abuser can be imprisoned for as little as 45 days whilst a male abuser gets 45 years for a very similar crime, albeit gender roles reversed. Something needs to change there.