We just got back from a week in Anaheim - our first time as a family to DL. We go to WDW regularly.
There are some distinct differences between the two, beyond size and location, that is. For one - the maps at DL/DCA do not indicate the locations of all food and shopping places. Research those in advance and have an idea of where they are. Second - the proximity of DL/DCA to local hotels, etc. makes everything a walkable distance. That's so different from WDW and it really did affect our trip - in a positive way.
Here are some thoughts we had - we found that the FP locations listed on many websites weren't necessarily the actual attractions that had FP. It wasn't a huge deal, but it was a small difference. Also - make sure you're fully educated on which FP rides aren't attached to the system - that made a world of difference for us. I would go into DL and pick up 2 FP right away. A couple of hours later I could get a couple more. Then at the end of the day we'd be doing 4 FP attractions in a row without a wait, which was always a great way to end a day.
You must try all of the rides/attractions that are DL/DCA only. Some of them are really amazing. Additionally, some of the attractions we thought were better at DL than at WDW were IASW, Autopia (Speedway), Tiki (we much prefer the original), the Railroad (gotta love those dioramas) and Fantasmic. For us, the others were either about the same, or better at WDW. Still we did all of them.
We had 5 park days (with the internet special 5 for the price of 3 ticket at Disneyland.com) and did everything we wanted to, and our favorites we did several times.
Be aware that the monorail is an attraction at DL. As a result, you might have substantial lines at times, and it only makes one loop - from Tomorrowland to DTD. It was a timesaver for us just once. The other time we rode it was just for fun.
We had a bunch of other observations about the differences between WDW and DL, but they weren't complaints or anything - just observations.
Enjoy!