The 24-105 is definitely not a "wow" lens. What it is, is the perfect walkaround general purpose zoom available for Canon FF cameras thanks it its relatively small size, light weight, constant aperture, weather sealing, fast AF, great range, IS and low price. If you have a crop camera, I would not recommend it because 24mm is not wide enough IMO. If you want a "wow" lens, look more into high end primes, they really will wow you. The Sigma 35 1.4 and Canon 135L are two of the cheapest "wow" factor lenses out there IMO. After those, it gets more expensive rather quickly.
I bought the 70-200 f4 IS as my first L lens. It did not wow me. It made me feel a bit ripped off in fact, I felt it was not worth $1300. So I returned it and bought the non-IS version, and that did impress me a lot. It was everything the IS version was (except for IS and weather sealing), at half the price. IMO if you're going to buy the f4 IS, never buy it new. I ended up buying a used one when I found a good deal and I'm much happier.