I'm also of the pre-cell phone era! And I've still got a landline. Don't want one of these fancy i-phones but can understand why people find them useful (especially in their jobs).

It is rude. Some people allow phones to rule their lives. Sadly, they then lack skills to hold conversations or deal with things verbally.

Yes, it can become an addiction. In the worst cases, people have had to seek professional help to wean themselves off.

One of the most frustrating experiences is being in a restaurant and couple at next table are constantly texting, even between mouthfuls of food