Here's a little report about my Nexus experience:
First of all, to clarify, Nexus is used when driving between the US and Canada, and when flying from the US into Canada. Global Entry is used when flying from Canada (and Israel - possibly others too) INTO the US. You get a Nexus card 10 days after your appt, and Global Entry is activated immediately at the appt - all you need to use it is your passport. It is valid for 5 years. You need to apply separately for every member of the family, but kids under 18 are free. After you apply online, you need to wait a few months until you get an email notifying you that you're conditionally approved and can now schedule an appt.
I had tried making an appt online, but the availability never matched up to when I was traveling. I walked into a Nexus enrollment center and despite their official policy of 'no walk-ins', they happily took my family in for an appt.
They call it an interview, but the bulk of the time was spent taking fingerprints, iris scans, pics, giving them your passport etc and they just made a drop of casual conversation about where I'm from, what I do etc. It seems they've already looked into you from your application and as stated online, once you are able to make an appt, you are already conditionally approved. The US agent who took fingerprints did specifically mention that the prints came back clean so they definitely run them through the system to check for a criminal history.
Note: I had to remove my contacts to do the initial iris scan (they took like 6 images). Luckily I had the case with me - make sure when going to your appt to either bring a case or not wear contacts. I wonder if going to a kiosk when traveling would work while wearing contacts or if they need to be removed every time!
For a family with kids: For driving there is no difference. However, for flying, they don't do iris scans or fingerprints on young kids (approx under 8 ). So the kids can have Nexus/Global Entry, but can't use the kiosk. They advise you to go to the Passport Desk for special needs/crew which never has a line.
I just used Global Entry with my family - At the entrance to the room with passport control there was a guy checking the passport and boarding pass (flying out of YYZ they do passport control before you fly). There was a mini line there, and I saw a sign in the room indicating where Nexus users go. I walked around the line figuring either I don't need to wait there because I go straight to the Kiosk/Crew booth or I should go to the front of the line. As I approached the agent I said I have Nexus, but he seemed unimpressed and said - 'There's a line'. While I wasn't impressed by that because in reality I should be able to skip or cut that line (what's the point in Nexus if I have to wait behind all the regular people to get to my fast lane?), once I got into the room I still got to cut a 10 minute passport line by going to the Crew Passport booth, and later got to go to a shorter line by security by mentioning that I have Nexus.
