I do. It was very noticable that it cut the fuel bills. Also, if I came home from work at lunchtime, instead of the house having got chilly in the 5 hours the heating had been off, it was still comfortable.
Prior to having it done, on a cold winters night (below freezing) the boiler (only a 14kW one) would be constantly running flat out; and if you ran a bath (demanding more heat to go to the cylinder) you would feel the house get cold.
After having it done, the boiler never needed to run flat out.
BTW if you get condensation, it is because the amount of moisture being generated in the house (the worst culprits are draping wet washing around the house, or on radiators; or having a shower without using an extractor fan) exceeds the amount of ventilation you are allowing. Modern DG windows are usually very draught-free, and some people refuse to ventilate. There area few scare stories put about by a very small minority, but I have never seen evidence of insulation being the cause of a problem.
In rare conditions, mostly where you have cavity walls which are in poor condition or leaky gutters and downpipes allowing rain to make them wet, cavity insulation can reduce the airflow inside the cavity which helps them to dry out. In this case the cure is to repoint the walls or repair the guttering. Some badly built houses have a lot of builders rubble or mortar droppings in the cavity, where the builders thought nobody would ever notice, and it is quite a job to get it out. The cavity companies are supposed to inspect for and point out any such problems before doing the work so you can have them rectified. If they fail to do this, you can demand compensation, and in some cases they will even vacuum the insulation out of the walls if you are a real nuisance.
I had some left-over insulation in a sack that I left out in the rain, and it filled with water. When I lifted the wool out, it drained immediately and was perfectly dry - it does not absorb water or get damp as you might have thought. Many years ago, injected plastic foam was used, and it had a reputation for cracking or letting fumes escape as it set. The modern stuff is inert glass or mineral wool.
I had mine done by Southern Electric. Most of the gas and electricity companies run a subsidised scheme, and as they are large and reputable, you can be confident they won't run off with your money or go bust leaving you with a worthless guarantee. As it happens I was very pleased with their standard of work, they cleaned up and matched the mortar in the brickwork perfectly and finished the job in less than a day.
Do the loft as well, it is important and very easy.
I believe BG is running a "free to our customers" scheme this year. Look at your energy supplier's website.