i have never driven the 1.5 diesel, but i had a 1.2 16v and its definately quicker than alot of other 1.2 16vs around! I have driven a few cars and my 1.2 was quicker than alot of the others. But if your looking for speed then a 1.2 aint gonna give you speed a 172 will !!! or 182!.
1.5 diesel will be quicker, I really enjoyed my little 1.2 dynamique has all the little extras, mine was just missing the air con.