Mine was 6 hours long.... with a DE no less. It was actually longer than my CFI initial at the local FSDO.
My ride was apparently pretty atypical in its length. The DE was one of the nicest I've ever worked with, but he was just very long. Covered the PTS and then some.
Besides the typical jaunt through the aircraft logbooks (he *didn't* ask to see evidence of the IFR-specific inspections to my surprise), we covered the IFR regs (all of them I think...), approach plates and enroute charts, weather, flight instruments (right down to which way the gyros were pointed in the AI, DG and TC), primary and supporting instruments for basic attitude flying, aeromedical factors (concentrating on spatial disorientation and hypoxia), the law of primacy again from the FOI, flight plan forms and alternates, and the maneuver lesson. I chose to teach him VOR holds and he actually let me go on for about 25 minutes, then spent another 10 or 15 giving me some alternative ways to teach them. Total Time, Oral: 3 hours.
In the air we covered all the basic attitude stuff: constant rate climbs and descents, constant airspeed climbs and descents, timed compass turns, steep turns and unusual attitudes. He had me "teach" him the unsual attitudes and that lesson went on for about 15 minutes or so. Then we headed off to do an ILS which turned out to be a circle-to-land approach, but the controller was nice enough to turn me on to the localizer 7 miles from the outer marker. We landed on that one and took a short break then went back out and did a partial panel VOR approach with a miss. And it was true partial panel with my AI and DG "failing" before I had intercepted the final approach course. So I did timed compass turns all the way in. Then we were vectored out so I could do my VOR hold. After that I just had to get him back to our departure airport without killing him which I did. Total Time, Flight: 2.4
Just as an aside, the winds at the surface were 18G26 and at altitude were about 40 knots. I almost decided not to do the flying part, but figured I might as well give it a shot since I have to teach in that stuff anyway. It seemed to work out okay, but I didn't quite get my VOR hold to work out the way I wanted to on the first lap. I had more wind correction than usual, but not quite enough. I explained what I'd do on the second lap and that satisfied him.
So that's my CFII checkride. Most people I talked to indicated theirs were about 1/2 that long and were a piece of cake. Mine wasn't really difficult, just looooonnnnnnggggg...
No real surprises on the flying except possibly how much of the basic attitude we covered at the beginning. I just assumed from everything I'd been hearing that it would be combined with actually doing the approaches.
One small thing though, I did the ride in a Skyhawk, but he had me tell him where I'd do things like lower the gear if I were in a complex airplane. We also discussed some manifold pressure and power settings for constant speed props on an approach, so even if you do the ride in something non-complex make sure you can speak on the subject.
On the oral I was actually surprised that he'd have me discuss the gryo instruments in so much detail. I brain-farted on which way the gyro is mounted in the AI and the DG. I also had to explain precession, tumbling (and caging mechanisms), and rigidity in space. All good topics, but not necessarily what I thought he'd be worried about me being able to teach.
I'd suggest reviewing the FOI material even though you don't technically need to (assuming this is not your initial instructor rating) because you can still be asked questions.
I took my CFI-I ride just over a week ago. All in all it was a great experience. The oral was about an hour to hour and a half long. We covered the six primary instruments, had me explain them and he didn't ask any questions. I explained explained the gyro's, how they worked and there orientation. I took the ride in a seminole, but he had me explain the systems of a 172. I also drew the vacuum system and explained the redundancy that is built into the system. After that we went into the regs and went through all the regs pertaining to IFR. He asked me a couple of questions about approach plates and enroute charts and we discussed lost comm. We also discussed the components of the ILS and the sensitivity of the localizer and how it changes with longer runways. The flight portion started with me explaining the before takeoff instrument checks and a normal takeoff. After climbout I contacted approach and requested my approaches. The first one was a two engine ILS followed by a missed at which time he took the controls and he wanted me to fail an engine on him. I failed the right engine on him as he was intercepting the localizer and he flew a single engine approach. On the missed I took the airplane and was flying to an IAF at which time he covered the AI and HSI. I flew one turn around the hold followed by a VOR approach. He took the controls just after the FAF and on the missed he flew us back to the airport and asked me how I would teach unusual attitude recoveries. At this time I was visual and he then put us in a diving right turn. I recovered and he asked me if I minded if he could land. The flight lasted 1.4 and was a great experience. I would highly recommend the DE, very relaxed and easy going.