Here's my 2p worth.

I am new to Rain X I only found out that the local halfords outlet sells it from this forum. I think it is great I have done both my windows and my better half's windows and I am pretty happy. There is a little smearing but I found that a new set of wipers (Bosch) sorted that.

So, no problems with me and I will continue to use it in the future.

 

I suppose it depends on the driving you do, but if you are having chronic problems with crap on your windscreen, it might be that you are driving too close to the car in front...