Then it gets annoying, because the shapeshift forms are they same for all chars so you are just repeating the same portion over and over again.
No, they aren't, not by a long chalk. They just look the same from the outside. The combat value of the various forms varies wildly with the Warden's stats, and hence their use in obliterating the enemy.
The versatility offered by the forms should allow any Warden - even a buffer/healer - to eliminate the opposition quickly and without fuss, with a wide range of different strategies even if you've played a similar character before. Slothy is a bit of an exception but there you can have your companions lend a hand if you want. And even with Sloth the forms do help a lot, as can be seen a few minutes later when you have to go against the weaker Uldred without that added power. For me Uldred always drives the point home that I'm a mere mortal again and no longer an unstoppable god of destruction.
What makes the Fade a bit less enjoyable for me is the blurriness, the low enemy density and level (since most of them are nerfed), and that some backtracking seems to be unavoidable. Keeping track of looted fonts can get a bit tedious if you have to replay from the last autosave because of a crash or because you hit a new level while in golem form.
What I find really tedious is Orzammar proper, with the endless running around and swatting of same-sized enemy groups, and the long, boring slog through the Carta hideout. The repetitiousness makes Jarvia's feel much longer than the initial romp through the Circle Tower even though they are of similar length (about 45 minutes for my current solo mage). The Fade seems a lot shorter.
However, I can see how things could get exceedingly tedious, if people just want to get it over with and try to muddle through. This pretty much guarantees that things take much longer than necessary, and makes them feel even longer still. That's what the mod is for, since even runscript killallhostiles would get tedious in such a situation.
P.S.: Blazo's post just came in and made mine a bit redundant... Ditto on everything Blazomancer said, and especially the Deep Roads.