Let's face it, the flying itself is easy. None of us here can pretend that flying a GA aircraft, especially after you've been doing it for 150 hours or more, is hard. So it all comes down to planning and organisation
I'd add "and a good understanding and appreciation of the dangers involved of flying in a certain type of environment."
and you don't have to be a grizzled pilot for that;
I'd argue that a grizzled pilot probably has a greater understanding and appreciation than someone with a mere 150 hours log time, and as a result has more chance of surviving any unexpected situation that he/she may find himself in. They probably have a greater chance of avoiding these situations in the first place.
Over the last couple of years there have been a number of high profile accidents in the USA which involved pilots who completely under-estimated what they were getting themselves into and have killed themselves and others in the process. When you look into the accident reports with the benfit of hindsight you have to wonder what they were thinking at the time. The only conclusion that I can come to is that they weren't at all prepared for the flying environment that they encountered.