Evolution is a big topic these days. Some people are really upset at evolution. I used to be upset about it too. I figured if there were no evolution we would all still be hanging out naked in the jungle. Then I realized that evolution also gave us waterslides, so it sort of evens out.
This Little Gamers strip from a few days ago got me thinking about evolution in web comics. It is a key thing that critics look for in a strip. We like to see the strip grown from what it was into what it is and to continue to become what it should be.
If you look at some of the strips that have been around for years, you'll notice a huge difference in the art style and quality. PVP, Penny Arcade and Questionable Content being some of the more popular examples that I can come up with without trying.
But remember, art isn't the only aspect of a strip that can and should evolve. Remember writing is just as important if not more so to success of a strip. The creator's skill at developing character and moving a story through the dialogue should be maturing and evolving as the strip ages.
There are plenty of strips whose evolution is solely in this range, often because these strips focus on writing rather than art, but not necessarily as those strips I've already mentioned have improved just as much in writing as drawing.
So strips, try to improve in what you do. Fans understand that a new art style isn't the only way to do so.