As stated above, I have only had this car for a week so these are my preliminary impressions.
Firstly, let me point out that this is the new face-lifted model which I own. Available since August 2004 I believe? It is a brand new car and only had 5 miles on the clock when I picked it up.
Let me begin by saying that the looks are outstanding. Personally I much prefer the new look ZR to the old one. The rear looks much better with its clean finish and reg plate set into the bumper. You also now get a nice meaty sports exhaust (even on the 105 which I have) and a very stylish steel heat guard above it. Very Sporty! I also paid extra on mine to get the 17" Alloys, Side sills and Rear bumper extensions. They all improve the look considerably adding more lines to the shape of the car.
Compared to my old 206 this is stunning. The interior is also excellent and by a large margin better than the old ZR. Nothing rattles, everything is very solid and in a nice position. Lots of silver finish around the trim gives a nice sporty look and the seats are equally as impressive. Compared to the stripped out look of the old ZR, I can't express enough how much of a jump this is.
As for performance. Well, I obviously have the bottom of the range model, but its still damn fast. My 206 was a 1.4 and it would be eating the Zr's dust. This is pretty much the fastest 1.4 on the market, even beating many 1.6 size engines by other manufacturers. The handling is also impressive, and I have never felt any loss of grip or body roll, even at high speeds on corners. The 206 has a high center of gravity and used to roll all over the place. I definitely prefer this.
The only bad point to make about this car, which is not really the fault of the manufacturers is the insurance. Because of the added performance and sporty look the costs do go up, but I feel its worth is and to be expected for a sporty car.
Finally, the price. I managed to get a really good deal on this car. Roughly £9200 (including the alloy, side sills and bumper extension upgrade). One disappointing thing would have been the cassette stereo which comes with the basic 105 I bought. I planned on upgrading this as soon as possible. However, as the factory had ran out of stock on tape decks they installed a lovely Kenwood CD player free of charge (guess they can't give you it with no stereo). This just sweetened the deal further. There is no other car on the market which looks and gives so much for the money!
All in all, buy this now!