It was brutal, but so worth it!
I summitted on Friday, October 5th around noon, starting from Outpost Camp at 4am that morning. Of our group of four, I was the only one to make it. But it should be noted that my friends who went with me decided to go just two weeks before, so they didn't really have time to train. I felt good at the top, but coming down I became dehydrated and ended up with a massive headache and puked at Outpost Camp.
Here are a few things that I learned along the way:
1) Make sure to do some high altitude hikes beforehand. I didn't train extensively, but I'm in fairly good shape and I did some strenuous hikes in the month preceding our permit dates. Rather than going out and drinking the weekend before (as I am apt to do), I hiked Mt. Tallac in Tahoe with my pack on. While Tallac is only 9,500 ft, I really believe that made a huge difference in my ability to summit.
2) Hydrate! This goes without saying, but it really will make or break you. My friend had to turn around after reaching the middle of the ridge at the top because she felt nauseous. She was dehydrated and had already finished her 3 liters of water, so I gave her 1 liter of mine and left her with the water filter. I was able to summit from Trail Camp and make it all the way back down to Outpost Camp with 2 liters feeling good (except for aching feet and knees). I finally drank some water with electrolytes at camp and started packing up our tent when a massive headache and nausea came on. I felt a little better after throwing up, but the final four miles were brutal.
3) Keep food close at hand at all times while hiking. This is really important. If your food is packed away, you won't eat as much. I was eating the whole time on the way up and it really helped keep my energy high and altitude sickness at bay. Compared to my hiking companions, I ate a ton and in hindsight I should have bugged them to eat more early on. Once altitude sickness hits, it's too late.
4) Invest in a good water filter. I used my Dad's old one that was slow going and leaked everywhere. When you're filtering freezing water before dawn, that's not a good thing!
5) Remember to keep your water in the tent while you sleep. My Camelbak tube was frozen when I woke up at Outpost Camp, which meant I had to filter water into a canteen at 4am in the freezing cold. Not fun!
6) Do what you can to sleep soundly. Whether it's having a super warm sleeping bag or bringing some Ibuprofen PM (if it doesn't make you groggy the next day), think about what you need to sleep well. I slept terribly at Whitney Portal and was kicking myself for not bringing Ibuprofen PM. At Outpost Camp I was pretty cold, even though I have a sub-freezing bag. I think if I had been more rested, it would have lessened my fatigue coming down.
7) And finally, stay positive! Whitney is like life. The hike is awe inspiring and beautiful, reminding one constantly of how lucky we are to be a part of this world. But it also is a grind, monotonous and mind numbing at times. And like life, the mountain presents its fair share of challenges, requiring perseverance and tough decisions.
Hope this helps. Good luck!