Hi,
I find the pace of advancement a little too fast.
Let me explain briefly. It is not as matter of PCs gaining too much power in short time but a matter of story development. Let's take the first two published adventures, KOTS and TL. PCs may take 1 week (in game's time) to explore the Keep and complete any missions therein. TL may take a little longer, but no more than 2 weeks exploring the labirinth. After that, PCs are already 7th heroes. They're close to become Paragons. In the Paragon tier this appear to be much more evident. I compare the Paragon tier to the Companion levels of basic D&D. PCs are great heroes known in civilized lands, at least in they're home regions. Let's take the figher, he may become a little leader of a small barony at 11th and then end at 20th as the legitimate ruler of a kingdom (by way of example). Can a DM properly handle such a PC's history in 10 levels? It's three adventures the size and complexity of KOTS. I think it's a too short time to develop a viable story.
All this said, given the limited time of playing for my group (one time a week), we are all appreciating the pace of advancement so far, but I foresee it shall rise some problems for the DM (me) in the future.
Best
Bran Mak Morn