My biggest peeve is the "boot-up" time required on my Canon PowerShot S200, which I acknowledge is a compact, entry-level model. To grab those candid, unstaged photographs one needs a camera that can be instantly triggered. My digital doesn't cut-the-mustard in that department, but my traditional 35mm is perfect. The second concern is image warehousing. Computer performance suffers unless you transfer resource-intensive digital photographs and short movies to CDs or another designated storage device. This cost should be factored when comparing to development costs and maintaining binders.
Fortunately, today's latest digital cameras have very fast startup times. I've played with the Casio EXILIM EX-Z40 and it starts up really quick, as does the Konica Minolta DiMAGE X50. As for warehousing your shots, given the cheap price of recordable optical discs in CD-R and DVD+R/DVD-R format nowadays that shouldn't be a problem. 
Hi RayChuang88-
Digital storage is not a problem in my case, because I'm somewhat of a geek. Explaining what needs to be done to family and friends can grow to be exhausting!
The solution to "digital lag" would be to upgrade to a more sophisticated camera. This is certainly my plan for the near future. If I can offer a single piece of advice to those considering new hardware...
Don't get SO concerned with size reduction that you sacrifice functionality!
The fact-of-the-matter is cameras are never truly pocket-sized, unless you don't mind feeling like a pack mule. One tends to carry them in a small bag belted to the hip with accessories like batteries, extra memory, and cleaning cloths. A few small inches in height, width, or depth is absolutely worth it to gain helpful features.
~ Blue Jays ~