I can't really answer that exhaustively, as I am not intimately familiar with all of GV. Phone Janitor does have some things I couldn't find in one package elsewhere that I wanted for managing my own stuff (some of which might be doable in GV? I'm not totally sure), and these include:

- Being able to route based on group, contact, time of day, day of week and to any phone number I want all in a single rule

- Linking my voicemails to family and friends without having to go through some authentication stuff I never saw a reason for (there's a story to this one actually, and I'll happily tell it to anyone interested)

- Not having to call anyone to access my voicemails

- Being actively developed on (this space seems rather stagnant to me from big tech. I have some tools options as a developer, but my parents can't really take advantage of any of that)

- Something I can integrate into other things I care about through some sort of API or export format or something (we chose the API route).

- Support. I don't need 24/7 instantaneous phone support (and don't want it, ideally) but somebody in the case of a huge issue should be contactable, fairly easily.

Even Phone Janitor isn't everything I want it to be (yet), but we've found customers find it incredibly useful, and we've had some good feedback for features that others will also find useful but still stick to our core goals (so ads probably won't be supported any time soon). Some of the feedback has been here today as you can see. I'm pleased with the criticism and praise we've received here, and I'm hoping to incorporate some of it into some progress in the near future.