Andrew,
I'm still currently on P1, there was a second grading session in April after the February one but that is not enough time to go from P1 to P2, generally need to give it about 3-4 months before considering another grading to get all the techniques under your belt.
Some new things to learn in P2 which are good fun are things like releasing from bar chokes or releasing from a choke on the ground, especially once you have bridged your opponent (push your hips off the floor and twist with your shoulders) at which point you should roll with them and be crouching or nearly standing and if the opportunity is there,

STOMP

! I think you can guess where

.
In general though I would the say the biggest difference is it gets your mind working far faster. Recently when my brother and I had a day trip down to Brighton I didn't have to use my skills but the car park we were in was not a bad one but the stairwell looked like the sort of one you see in training examples of Krav Maga and I was walking down the stairs thinking if someone appears with a knife how do I deal with them?
As with all martial arts/defence techniques, they don't make you into a sort of super human fighting machine who if someone taps on the shoulder you'll break them in two, but it does leave you feeling far better prepared especially if as the situation above outlined occurs you know you have the advantage of height and a pair of size 11 boots, plus the speed is the major thing in Krav Maga, the speed of the attacks I practice now is staggering, that is definitely the biggest change now is that my attacks and defences flow far more quickly and smoothly than they did when I started.
On the whole though its still bloody good fun to learn, even if I do get a bit of a sharp whack every once in a while, it reminds you of reality and also if thats how it felt during training, imagine what the other guy will feel if you have to do it for real. Plus its nice walking away thinking you've learned something that may really come in handy one day.
Plus the syllabus is fairly easy to follow once as our instructor once put it, is converted from Hebrew to Israeli english and then to english englsih lol.
An example though is the release from a choke on the ground:
1) Pluck attackers hand with one hand, circular punch with the other
2) Bridge and roll to the side
3)
Counter Attackin general though whilst I'm still enjoying it and learning something new each time I go I'll stick with it. I even did one training session with my left eye covered, right is the really bad one (I don't train with my RGP's in for obvious reasons) to see how I got on, didn't do too badly as it turned out. Defending against a knife attack was a bit difficult but I just used an outside knife defence and a solid kick to the groin and then I was off. Hopefully though I'll never be in that situation in real life but if I am, well shoot, it'll be time to find out if I was actually paying attention lol.
Still like I say, Jason Bourne has nothing on me
Jez.
If you break a leg hop along on the other one, if you break the other leg shuffle along on your backside, if you've got piles its your unlucky day.