Not wanting to be difficult but I now have a few jobs where I do the internal cleaning with these pads. I'm not saying the dragonfly is the best route but the cleaning principle generally works OK so long as you work in a certain way.
My observations are as follows:-
Forget it on first cleans or very infrequent cleans (I have a quarterly internal clean that works OK). If you must use it on first cleans, make sure you have a lot of pads and be prepared to go over it a second time with fresh pads. Even then it may not look great but follow up cleans will get better.
Be VERY sparing with the spray water. Too much can lead to poorer results.
Use de-ionised water - just in case.
Although someone did assure me differently, after washing the pads, I do hand wash and rinse them with de-ionised water before drying them. I did a dodgy job with these - the only one so far (apart from the first when I was experimenting) and I believe it may have been because I dried them after they had been machine washed - without the after soak in de-ionised.
DO have a lot of clean pads - the number supplied with the kit isn't enough.
Generally the results are good enough. If inspecting closely though, there may be the odd gremlin but that can happen anyway. Probably better not to use them on domestic where it may come under much closer scrutiny.
It's very useful for offices or the type of job where lots of paperwork is left on sills etc. Sometimes a wagtail (or similar) won't be the right tool because of the risk of soaking the sills.
It's certainly worth having a pole and pads just for the odd window that can't be negotiated safely. I tend to use them on all the inside office windows though. It cuts the time by half.