I have leveled from 1-60 under the new system and kept track of how long each level took.

First some background, I have leveled over 20 characters to 100 with a full contingent of 110. I started playing in Vanilla, but leveled all current max level toons after Cataclysm. This is wearing full heirlooms. I played an Orc Mage. I avoided all rest xp except for the minor bump you get from logging out anywhere.Valley of Honor > Northern Barrens > Ashenvale > Stonetalon > Southern Barrens > Dustwallow Marsh > Northern Strangelthorn > Southern STV > Western Plaguelands > Eastern Plaguelands > Ghostlands > OutlandIn total, 1-60 took 19 hours, 45 minutes, and 19 seconds of playtime. We're going to call that 20 hours. Here is a chart showing the time it took to go from one level to the next.While I have not tracked a time to sixty in several years, my most recent toon, which was leveled primarily through dungeons, is a lvl 65 warlock with 25 hours of playtime. This would track appropriately for my current data with each level over 60 taking a little under an hour each. There is a noticeable spike in time to level at level 58 jumping from an average of 30 minutes to 45 minutes. Otherwise, the curve in time to level is smooth from 10 to 58, gradually increasing from 10 minutes to 30 minutes.It is my conclusion that the time to level to 60 has not changed. For everyone saying that it is taking longer, this is a psychological difference. Dungeon running would usually get 1 and 1/2 levels on the first run, with 75% of repeated runs. For lower levels this meant you only ever saw a dungeon once, but as you passed 40 you saw many more repeats. Ultimately the time investment was the same though the progress came in large waves rather than a sustained flow. Additionally, leveling through questing requires a more active engagement than following around a tank or running the same old route through a dungeon.TL;DR - Leveling in 7.3.5 has a negligible change in time to level, but significantly more freedom and variety.PS- This isn't an observation on whether or not it should take that long to level, only that you're no worse off in 7.3.5 than you were in 7.3.