Would you regret a car engine downgrade?

I have a ford fiesta zetec 1.4l 2005 and want to buy a new corsa limited edition 1.2l 2014. If you go from a 1.4 to a 1.2, would it annoy me not being able to accelerate as quick? Would i notice it?
Also, my friends new corsa 1.2l engine has a better sound than my car, why is this? Just coz its newer?

Better sound? Best would be no sound.
No one here knows whether you will notice it or whether it will annoy you - how could they?

The difference between a 1.4 and a 1.2 liter is negligible. I own a 5 liter V8 with just under 500 horsepower at the back wheels. If I had to drop back to a 1.2 liter engine the difference would be significant, in fact I think the 1.2 liter engine would have a hard time trying to move a ton of steel around. But in your case it is only 200 cc's of capacity. As a word to the wise a smaller engine is ideal for suburbia, but if you live in low population area's a larger engine will offer better fuel economy and will need to work less than a tiny engine. If you do a bit of country driving a 6 cylinder is good. If you do a lot of country miles a V8 is your best bet. Several years ago I drove my V8 1000 miles and it used less than 40 gallons of fuel at 80 miles an hour in 100+ degree heat. A baby 4 cylinder would of given up the ghost or used a lot of fuel trying to keep up.

You are never going to accelerate quick with either of them and chances are the 1.2 is faster than the 1.4 as Ford have never produced a quick 1.4 as it is built for economy.