Its good if you want a tempery effect.
Thing is with clay initialy depending on how bad your paint is to begin with it leaves it smooth to the touch but can leave alot of marring and deep swirlmarks. It removes most of the bonded contaminates depending how deep they are but also can damage the paint when there removed. The finish from the clay will generally last from anything 3 -6 months depending on how much you drive it.
To reduce the marring and the swirl marks you normally have to cut down the clear coat with an abrassive polish to remove them then seal it with a sealent or glaze then give it a good few coats of wax to ensure the finish is long lasting, providing its washed, dried and waxed correctly and not too often you shouldnt have to clay or polish your car for a year, just keep it topped up with wax and you should maintain a decent finish.
The polish thats in the kit will mostly only fill in the swirl marks and after a month or so will eventually evapourate and leave the paint unprotected showing up all the swirlmarks and marring.
IMO your best getting a better clay and using the residual water from rinsing after washing plus maby abit more to lubricate it as you go, then give the car a wash again. Invest in a decent polish or sealent and also a wax, it cost abit more extra initially but the results will last alot longer and youll need alot less effort after the initial clay to maintain the finish.
Heres a decent all in one once youve clayed
http://www.cleanyourcar.co.uk/polish.../prod_166.html