I climb at least 5 to 10 times per week..... It's not too difficult, however free climbing is a thing of the past. We now use a fall restraint system called the buck squeeze. It makes climbing a little harder and your pretty tired by the time you get to the top of pole.
The linemen here are lazy. They all use bucket trucks. On some very old poles left here though, there are several giant pegs in the wood that i guess acted like some sort of ladder from before bucket trucks were used. The pegs start about 10 feet off the ground and go up to the top of the pole.
I work for the public utility up here in Massachusetts but I work in the substations such as the giant transformers and transmissions switches. Pretty sweet job.