My wife has an M&P 40, so therefore it's a girly gun.
Seriously, she's probably got about 5-600 rounds through it, and so far we haven't had any problems. Seems to handle a wide range of ammo without problems, and seems pretty accurate. My wife has small hands, so the adjustable grip sizes were a big advantage for her.
As you probably know, it is a full size pistol, so it will work well for a home defense gun, but it's probably a bit big for concealed carry if that's an issue.
I like .40, but I think 9mm can work as a self defense round if you choose the right round (and .45 obviously will work as well). More important is what will allow you to put more lead on target, which to some extent will be determined by how much you practice with it. Ammo is a bit more for .40 vs. 9mm, so keep that in mind. If that affects how much you will practice with the weapon you may be better off with something that shoots cheaper ammo. Of course, around here in So Cal .40 ammo is pretty readily available nowadays, but 9mm can be tough to find. Not sure about other areas of the country.
I'm not sure I can explain the details of what striker fired action is, but I think that is what all the semi-auto pistols without an exposed hammer use, so that would include Glocks, XDs, and so on.
I like the trigger pull on the M&P better than the trigger on a Glock. It seems a bit lighter, although it is a long pull typical of a DA only pistol. Obviously, that's mainly a question of personal preference.
I think it's a fine choice if it fits your hands comfortably. You might want to see if you can find a range where you can rent one and try before you buy.