I had the autogym lifeshine done on my car, it got it FOC due to dealer error over my courtesy car. To be honest, the outside finish and protection is no better than a good polish/wax.
The inside, carpets and leather gets a coating of something, and this is worthwhile. It resists spills and i recently spilt some coffee on the carpet and it just lay on top, and wiped off leaving no mark at all.
As regards tracker, there are only 3 main ways to steal a car now..
1. Steal your keys, either from you or your house.
2. Break the window, release the handbrake, knock out of gear, overcome the steering lock and tow away
3. Full lift onto lorry/front suspended tow
However cars do still get stolen and I would have tracker fitted personally.