Having leveled 5 characters up through 11 levels: keeping track of all the numbers is a big deal. If you have looked at any of the pre-generated character sheets you may have noticed all of the end-notes (all 30+ of them): This has been the only way I could keep track of all the numbers.
Now in the real world, where a player need only keep track of their character, and leveling occurs every few sessions (assuming 10 encounters, with 2-3 encounters a session, it should happen every third or fourth session); The math should not be too much of a problem. I would, however, suggest that Players keep track good notes on what effects what.
Keep in mind that I am not using A spread sheet or any other tool. Just word, calculator and CutePDF. In a better world I would have started with a spread sheet for each PC or used one of the available tools. In the perfict world, there would be a sanction WotC application that would remove all of this drugery.
This is not a complaint, just a minor venting after a full day of rolling the party through levels.