The ADDeRabbi has a review of the Artscroll women's siddur here. and a further comment here. I had earlier posted my objections to the Artscroll translation/commentary on Shir ha'Shirim. The bottom line is that certainly Artscroll has made many texts available to many many non-Hebrew speakers. They have simplified learning. But they have also used their Bill Gates-like near monopoly(not their fault that they have this monopoly, but it is one none the less) to promulgate their view of Judaism, rather than a more ecumenical(covering the spectrum of orthodoxy, I am not meaning that they need to include reform perspectives) Orthodox view. Since Judaism takes "facts on the ground" into account in issues of Law(minhag has halachic power) establishing "minhag artscroll" and reinforcing it via myriads of publications diminishes those who do not hold by this minhag. Also, by presenting one view as THE Way when in reality there are a number of legitimate opinions, Artscroll manages to eliminate any debate or thinking from those whose sole source of information is Rabbenu Artscroll.
While I certainly agree that they are entitled to print what they want, and to push their viewpoint above any other, It is wrong to portray halacha as a monolith supporting only what they see as correct.