Ooooh, I'll just warn everyone over there, will I?!
Seriously though, I'd recommend it to everyone. There's paddling for every level, people learn to paddle from scratch over there. The playboating is awesome and there are so many different lines down each rapid, and so many different channels to explore when you've exhausted the commercially rafted runs. They still kept me entertained after three months, although I'd be a bit slower than most, considering I couldn't roll properly when I got there.
Re: rolling, its a great place to learn, but unless you have a long time out there, you would want to have a solid roll - getting up first time almost all the time. If you don't you will still have a great time, but you might not get as much out of the trip as you would if you had a bombproof roll. I know that I only really started getting places when I got it down pat. Swimming 15 times in three days on Nile Special was no bother, but imagine how much more surfing time you would have if you're not swimming a mile downstream every time you try to catch the wave!
I think you could consider a club trip over there. It is expensive to get to, but then when you get there, it's dirt cheap.
Book your flights through kayakthenile.com or you may find yourself sans un kayak over there.
And don't get into a headbutting contest with Jack. Even if he gives you a helmet.