I opted for the Wagon R primarily for the space it offers. Since it has a tall boy design, getting in and getting out esp. for senior citizens like my parents is very easy. The ride quality is good and it also has a reasonable ground clearance if we take it outside the city. The A/C is supercool. My kids also love it as you can fold the rear seats and have enough space at the rear.
The car is very easy to drive in the city because of the torque and you do not have to change gears often. Even at 25 mph, it will ride in the 3rd gear with the A/C on. The fuel consumption is also good and it returns about 12.5 kmpl in the city traffic like that of Mumbai. I have taken the car outside Mumbai in Maharashtra where I have got a mileage of over 19 kmpl. I have observed that mileage depends basically on how you drive the car.
About 6 months ago I have got an LPG kit fitted from an authorised Maruti dealer. It has a torroidal tank in place of the stepny so I have not compromised on the boot space except that the spare tyre is in the boot. But that is fine. On a full tank of 28 kg of gas I could cover about 420 kms on a long drive which I found to be good. The only issue with the gas kit is that it has to be properly tuned otherwise there is a problem with the mileage and the pickup. There is a problem though with the LPG gauge as it does not indicate the right amount of gas consumed/ available in the tank. I have found that even in the LPG mode there is no loss of power as some people say. If one goes for an outstation drive the running cost is comparable to that of sleeper class fare of the railways or the deluxe bus fare fro a family of 4/
Overall I would say that the Wagon R is true value for money at the price it is available though it could be cheaper after the arrival of some other models in the year 2007.