Wow, pretty good reviews. I've eaten at two of the places they mention in that Washington Post review (Oceanaire and Jerry's) and thier crabcakes are excellent so if your sister's place is comparable, there should be no worries. Plus the fact that they actually use Maryland crab as opposed to Indonesian is suprising since most places use Indonesian blue crab.
Well I went to Bobby's Crabcakes last night and I have to tell you I was impressed. The crabcakes are definitely in my top 5 places in MD to get crabcakes and the fries are awesome. The crabcakes had hardly any filler which is sometimes not the norm even for some of the other top places. Unfortunately the owners were not there by the time we got there but I will definitely be back next time I'm out that way. The restaurant is also in a great area so if you are out that way give it a shot. There are other items on the menu if you don't like crabcakes that also looked pretty good so I may have to try a couple different things off the menu.