At a prompt from my phone, I switched on Google Now, just to see what it was like. On a positive note, I like that it warns me in advance of traffic delays between wherever I am and home and work, as long as I remember to check. What's more, I didn't have to tell it where I work, it just figured it out, presumably from where I spend most of my working hours. That's both cool and a little bit scary. The weather alerts work about the same as my previous alert widget, so that's kind of a neutral change. The big negative aspect is what it did to my calendar reminders.
I rely on getting audible reminders from my phone about upcoming appointments, and Google Now does provide cards on that, but it does so in complete silence and invisibility until I go to check. At that point, I always see a weather alert, plus maybe a note that says I've got "other cards" to display. Tapping that button gives a several-second delay that might, eventually, tell me about the appointment I missed half an hour ago because of the silent "reminder". I found that I had to disable Google Now for my calendar, then turn reminders back on in my calendar app. I can live with that, but it seems like an odd implementation choice.
I've seen a couple of cards for nearby restaurants, which I thought was interesting at first, but now it seems more like advertising to me. "Hey, I noticed you're near the Hog's Breath Cafe! Why not stop in for a steak?" When I'm looking for somewhere to go, it might be good, but Google can't know when that is.
I've also started using the reminders system via voice commands. "Remind me tomorrow morning to call Dad". "Remind me when I'm at the shops to pick up milk". Location-based reminders are really handy, and creating them in natural speech is a huge plus.
Mokalus of Borg
PS - Google Keep also does location reminders now.
PPS - You just can't set them up the same way.