We've been to both DLR and WDW many times although DLR far more. They're two very different experiences but equally great. For us WDW's dining selections are a big part of our vacation at WDW. We enjoy the free dining that allows us to go out for a nice dinner each night as well as a good lunch. Because of this its a slower paced vacation and thus we go for 6-8 days.
DLR has 80% of the rides, shows and attractions in 2 parks as WDW's 4. Both parks, Downtown Disney and 3 onsite resorts as well as many offsite are all in walking distance from each other. Park Hopping is totally different than WDW. Its common for us to go back and forth between the two a couple times in a single day as they're only 5 minutes walk. Because of the compactness we get alot more done each day and thus DLR is great for a 3 or 4 day vacation.
At DLR there are no busses, boats etc. to bother with that take up considerable time. The monorail really isn't used as a form of transportation like WDW. It's more of a ride although it does connect Downtown Disney to Tomorrowland inside
Disneyland (15-20 min walk at most). That means a valid park pass is required to use the monorail.
As noted there is no such thing as free dining at DLR. There are some great restaurants but a small fraction of whats available at WDW. Also note that there are only 3 onsite hotels, all Deluxe. There are numerous 1 to 3 star hotels in walking distance and many 3 and above resorts just down the road. All have their own shuttles to DLR or use the cities hotel/disney shuttle service (ART).
We will be at DLR next month for 4 1/2 days then San Diego for 2. We'll be staying near Knotts Berry Farm about 5 miles from DLR as hotel prices are much lower and we have our own car. Can't wait!!