Fly pretty much hit the nail on the head, but a few other things to consider (I just completed so I can afford to take the time to have some bourbon and philosophize on a weekday, apologies for the long post

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In college, I ran a marathon. If you take flight school as a whole as a similar long-time, long-distance test of motivation, I definitely hit the proverbial wall in flight school about the same time I did in the race. Mile 18 or so, just felt like hell on earth and the end was nowhere in sight. Similar feeling about the end of Phase I, beginning of Phase II. I had a hard time at first and was really frustrated at my grades. The moral is to KEEP PLUGGING no matter what. Don't think that just because you completed RIs in Primary that instrument approaches are a piece of cake. In theory, yes. in practice, no. The Goshawk will humble you if you let it. Get in the sim and practice constantly.
Few people get through the program without any pink in their jacket (only one guy in my class of 6), which is a slap in the face after Primary, where you have to be pretty damn good just to get here. Dust yourself off, learn from the experience and keep going. And remember, the jerk has as much to teach you as the "cool" IP. It's possible to go from rock star in T-34 land to average schmuck (or worse) in Advanced. The bell curve has shifted.
There is more of a wardroom atmosphere in Advanced than Primary, especially as you get close to the end. Though the student/instructor gap is still there (as it should be), it's a little less pronounced. IPs will get to know you by name (and callsign in later parts of Phase II) and you'll feel more a part of the unit than just a random guy there for 6 months. Granted, you still "sir" them, etc.
Finally, I remember the confidence I had in my little Turbo-weenie at the end of Primary, but I never really knew what it meant to be one with an airplane until the end of Advanced. You stop thinking about the monkey skills and just put the airplane where your brain says it has to go. I remember early on worrying about all the solo time, but frankly it's the best part of the syllabus. You're being judged on your actions alone, without an IP to rescue you if you screw up. Tons of fun.
And there's no better feeling than overnighting on an aircraft carrier with your buds, wandering the flight deck surrounded by jets that
YOU PUT THERE. Proudest moment of my life. You'll love it.