i have the Sport 42, i put off buying it but i got it as a present from my family. i must say, it's a great watch. the notifications on your watch makes you not look at your phone as much which is good, the workout apps (Activity and Nike+) are great, helps you stay in shape. has not affected my iPhones battery life at all.
BUT at the end of the day it is still a watch. it depends on the person, if your are going to over use the Watch, (text, calls, games) sure it can be a good thing but you can also drain it's battery faster and that might be frustrating. so it truly depends, and you wont know until you own one, we are all different and use it differently.