I don't have a droid so can't try your app, but I use the MDC app on iOS. I have a number of whinges about that app but the main one is: allow me to specify an arbitrarily long list of process steps. The reason I say that is that I want the timer to be useful for B&W, C41, E6 and RA4, each of which has a different selection of steps. Currently I hack around it in MDC by putting my bleach+fix times as Fix1 and Fix2 and manually (woe!) timing the pre-bleach, reversal and all the other steps including washes. That sucks.
It'd be very cool if you had an "Edit Program" Activity showing the process steps in a program and permitting the user to edit the name/time/comment on each step, plus a button for an "Add Step" Activity. So for E6, I'd end up with (I think) an 11-step process including all the washes.
Request #2: use a different warning tone for "end of process-step approaching" at a user-settable time-in-advance. MDC has three beeps before agitation begins and if your process ends on an agitation boundary then you get the three beeps. A couple of times I've been processing by ear and not looking at the display, picked the tank up on the beeps and then swore a bunch while I hastily tried to get the lid off and dump the chems on hearing the end-of-process alarm right after that.
Oh yeah, and MDC breaks (!) your custom development settings on some upgrades, e.g. deleting the Fix step altogether and adding in a hypo-clear step you didn't want. Bad. Modifying the set of available steps in a process should not be a code upgrade, it should be (as per my first request) merely data within a given process program.
If you want to be uber-fancy, allow variants on a process, e.g. "N", "N+1", "N-1" etc that match up with the recorded outputs from your metering/BTZS-alike app. You should be able to retrieve the list of rolls/sheets shot, say "I am developing this one" and have the process-timer fill in the appropriate dev time given the selected SBR/CI of the logged exposures.