First, I can definitely recommend getting a smartphone. I'm normally a late adoptor, but I am glad I switched relatively early to a smartphone. I ran into people now and then who tell me they don't need their phone to do X, they just want to call people, but I'm sure once they have all the functionality in one device they would never give it back.
Regarding risks, I ran into a problem with the custom MIUI ROM where I couldn't boot the phone anymore. I was scared there for a second (since I couldn't even get into the recovery mode) but I just found the current official Samsung firmware, flashed it and everything ran fine again. You can tell though that it has been modified, since each flash of a firmware increase an internal counter. So in theory there is always the risk of a bricked phone or voided warranty. But I don't know anybody who had this happen.
For me, so far it's been a lifestyle choice. Seeing the extent to which I am addicted to my computer and am totally glued to it when it's turned on, I am scared the same will happen with a smartphone. On the other hand, being able to look something up quickly on a smartphone might make it easier to keep the computer off and engage with life.
FWIW, I was once like you and resisted getting a smartphone for quite a while. Now I'm no longer chained to my desk. I can go on an epic bike ride, chart it with GPS, and never miss an important email. If anything, the smartphone has given me more freedom, improved my health, and increased my awareness of my surroundings (never get lost, locate nearby businesses/attractions, leave the house more often). The nice thing about a smartphone is that it spends most of the time in your pocket. You only pull it out when you need it.
Regarding risks, I ran into a problem with the custom MIUI ROM where I couldn't boot the phone anymore. I was scared there for a second (since I couldn't even get into the recovery mode) but I just found the current official Samsung firmware, flashed it and everything ran fine again. You can tell though that it has been modified, since each flash of a firmware increase an internal counter. So in theory there is always the risk of a bricked phone or voided warranty. But I don't know anybody who had this happen.