We actually just booked an NCL cruise this past week after doing Carnival the past couple times.
Regarding the offers, read the fine print. It's technically not as good as you are led to believe. The "free excursions", for example, you get $50 towards ONE excursion for ONE person....not $50 towards excursions for both a husband and wife in a stateroom. For the "free unlimited drink package", it will cost you about $125 in gratuities/fees (assuming this is a 7 day cruise). This might be a great bargain depending on how much you drink but still...it's something to keep in mind.
I think the "free wifi" is something like 120 to 150 minutes during the 7 day cruise.
Summary: The offers are nice but not as good as you think they might be at first glance.