I love BabyFeedingLog, have used for 2 babies now. I like the simplicity and that data can be added later. I don't really use the sleep function. It worked great for my healthy first born, but there are a few things I would find useful for my second baby (who has tummy problems):
1) another "tab" for time medication was given, possibly with a function for a reminder of next dosage
2) commenting ability for each feeding and diaper
3) for bottle feedings, choice of breastmilk or formula
4) provide duration of feeding in addition to start and stop times
5) 5 minutes after hitting "pause", have an indicator sound to remind me that "continue" hasn't been pressed yet
Other functionality ideas:
-A red-tone night light
-Additional babies (for mamas with twins/multiples)