We have been to WDW many many times over the years, but we decided to try on DL this past May and had an amazing time! It was great with DS (18 months old at the time) to be able to just walk between the two parks instead of having to trek out to the car, fold up the stroller, etc. and drive to the next park. In fact, we loved it so much that when deciding whether to go to WDW or back to DL for our anniversary trip in August, DH and I picked going back to DL. So we have been twice this year! It is wonderful for shorter vacations, whereas if you are looking for a week long destination, WDW is the way to go (unless you are planning to go to other attractions in SoCal, but strictly comparing Disney park to Disney park).
We loved getting to experience so many new rides (Monsters Inc, California Screamin, some of the dark rides in Fantasyland, Matterhorn, Cars Land, all of the attractions in Bugs Land which DS loved, Indiana Jones) and different versions of rides we already love in WDW. Space Mountain is so so so much better in DL!
In reading the responses, a lot of people complained about the CM's not being as friendly, and we found totally the opposite. Every CM we interacted with was so friendly and helpful! I can't think of a bad experience with a single one of them, and most actually went above & beyond for us.
Since we are from Louisiana (and our Premier AP's expire in November

) it is unlikely DL will ever become our "home" park, but we will definitely plan to go back every few years. I didn't think I would like visiting DL after so many trips to WDW, but our family absolutely loved it!! After becoming so used to WDW and knowing the parks like the back of my hand, it was nice to discover new attractions and to not know what was around the corner when walking around DL.