I found the GAPAN testing a very positive experience. The de-brief was well constructed and most importantly honest. The gentleman who spoke to me was an ex-BA training Captain, and as I sat in front of him I expected to hear the words 'not a chance' and 'forget about it' creep up. However I could not have been further from the truth, and I came out with an extremely positive outlook on the situation. Although it was only an indication on my chance of success, I hope it's spot on!
GAPAN testing in my view is worthwhile, and could save you quite a bit of money!
Good luck