Depending on who you talk to the military press is either part-God or all-Devil. I am part of the faction that believes that the military press is a great exercise, especially when done in moderation. By moderation, I mean performing them for 3-4 weeks at a time and then moving on.
Having said that, I believe that the military press is perfect for building shoulder strength. You can do all the lateral raises you want; it simply won't compare to pressing a barbell overhead. Not only will it build your shoulders, but I also noticed a lot of upper back development. Bang for buck, you won't find a better exercise for your shoulders.
I also believe this exercise is a great way to build your low end strength for the bench press. Many great pressers have used this exercise as a way to strengthen their bench presses.
I think many people who say this exercise sucks are those that have shoulder injuries and cannot do it. It's like those people who have "bad knees" and say that leg presses work just as well as squats. It's just a way for them to make themselves feel better.
Having said that (I sound like I am a lobbyist for the military press), I like to use this exercise as a supplemental lift, but done for higher reps (6-10). I have used lower reps, but this was more of a spur of the moment thing.
3-5 sets of 6-10 reps works well. I like to do this as a 2nd exercise after my core lift of the day.
You can use any grip that you want, but have found that a close to medium grip works well. There is little strain on the shoulders while still strengthening them to a high degree.
The military press is actually a variation of the standard overhead barbell press. The difference is that when performing the military press, your heels will be touching. Well, that's how it's supposed to be... but the lines between military press and overhead press have become so blurred over the years that the differences are not even worth arguing. Just press the weight overhead!