When I first started college I knew I was going to leave to join the Army. I wanted to study law but the parents wanted me to do medicine. In rebellion I joined the army and whilst in college took BTEC Computing or something similar. I lasted about 3 months and was clawing my eyes out at the banal CoPE standard of work. I kicked and kicked until they let me change to take 5 As Levels, which I then carried on with in A2 until I left for the army late in my second year.
I found the BTEC was full of 'vocational' people. They were not very academically enlightened and it felt like being in a low set GCSE class.
I think BTEC is great for people who aren't academic enough to show themselves off at A2. It allows the more practical of the bunch to shine through coursework. People who take BTECs can do well, but are quite often limited to low level professional work later on in life.
It all depends on your interests, strengths and aspirations.