We had a great trip despite the weather and unexpected difficulty. We pretty much knew what we were getting into as far as the weather with it being the rainy season but we weren't sure when we'd be back in Peru and didn't want to miss out on the opportunity to do the Inca Trail and see Machu Picchu.
As for the difficulty, we were not in nearly as good of shape as we thought we were and underestimated the effects that the altitude would have under exertion. The classic term during the trek was "Peruvian Flat" which really meant up and down without much net elevation change. Definitely not the flat I know. I honestly expected a fairly leisurely hike with a few areas of moderate difficulty. We gained something like 4500 feet of elevation in one day up to nearly 14000 feet on the 2nd day. Nothing leisurely about that. Especially with a 50 pound pack on your back.
Anyway, on to the actual guide service. I'm not sure how it could have been any better honestly. The food was amazing, guides were friendly and the porters were some of the hardest working people you will ever see. Views and experience were indescribable. Has to be experienced for oneself.
My recommendations would be to pack light, hire a porter to help with your stuff, allow a couple days in Cuzco to acclimate to the altitude, and go during the dry season. We did none of this and still had a great time but these things would have made it even better. Oh yeah, and work out before you come :)