Agudah does a lot of good.
Nevertheless, as I have mentioned here, many times, they are on the wrong side of the Zionism issue. The fact that they declared the state illegitimate 25 years before it was founded, and have never come to grips with it, shows a confusion in dealing with current reality. They never acknowledge the good that it has done, and do not show hakaras hatov to the soldiers who are constantly being moser nefesh for the klal. They are allergic to any mention of the medinah in tefilos, such as a misheberach for the medinah or the misheberach for the chayalim.
In addition, there are at least as many non-Agudah gedolim who supported Zionism, but they are never acknowledged.
They have consistently opposed YU on the grounds that it is Torah Umada, and opposed all college for that matter until recently. They are now waking up to the fact that it is necessary for parnasa, but will never admit that the YU approach was right all along. (Touro is basically a carbon-copy of YU, but they make it seem like it is a tremendous new innovation which is somehow kosher now. It is because they will not retract or apologize for their old position against YU, that they grasp at straws to find differences between Touro and YU. Touro was actually started by YU people.)
They have always opposed Chabad and the Lubavitcher Rebbe, not just in shita, and not because of the meshichism, but beginning for many years before that and possibly from the days of the previous Rebbe. They constantly launched vehement personal attacks against them. This despite the fact that the last and the previous Rebbes (and all the rest of the Chabad rebbes) were unquestionably from the greatest gedolim of the generation. (The Rebbe has over 100 sefarim of his sichos and writings on all areas of nigleh and nistar.)
They have done much good in polishing the image of Torah and making it available to the masses, and encouraging a rebuilding of advanced Torah learning since the holocaust and the building of many yeshivos. However, the primary problem is that they do not give proper respect to other equally valid views. Remember that the halacha is like Beis Hillel, because “Shonim divreihem vdivrei Bais Shammai.” Beis Hillel always first cited and explained the views of Beis Shammai, and only then would respectfully disagree. Agudah is not goreis any other opinions.
PS. Regarding the mixed seating issue, I have heard that all Reb Moshe’s children’s weddings were mixed. But I just now heard a mayseh about someone who was invited to a mixed simcha and asked Reb Shmuel Kaminetsky if he can go. Reb Shmuel told him that Reb Aharon Kotler made 3 weddings for his kids, and all were mixed, as well. It seems like it is basically a chassidishe custom which has crept into the heimisher world recently. (I personally think that it is because anytime anybody has a new chumra, he can very easily make anybody who doesn’t hold of it seem like a kofer and a rasha, while the person who does what was always the minhag has no strong argument and is always made to feel guilty. So the biggest chumra always wins. This is despite the fact that Chazal say koach dhetera adif.)
So the bottom line is that Agudah has played an important role in rebuilding Torah, but their acrimonious attitudes to other groups has cause terrible sinas chinam and major rifts in klal yisroel in place of what should be shalom and ahavah for all yidden. A generation ago, one would find the finest children were from chareidi homes. They were sweet, friendly, sincere, devoted to learning and always looking to do chesed. Now unfortunately, some of them spend a lot of energy snickering at other Jews and groups and telling loshon hora. This developed because they heard their leaders putting down other Jews. I firmly believe that if all charedim stopped loshon hora completely against all other groups and the state of Israel, no kids would ever go off the derech. They would see such fine midos at home and at school that they would never think of leaving such a gan eden.