GW2 is addictive enough to keep you going but what's really great about it is the amount of content being added every 2 weeks. The community, for the most part, is pretty good and the game itself has a lot to offer. The $50 price-tag is definitely worth it and no monthly subscriptions.
The game has a lot to offer for the casual community but it also gives end-game enthusiasts things to busy themselves with once they reach "the peak".
Just returned after a 9-month hiatus from the game about a month and a half ago. I had one Lv80 (max and geared) when I left and now I have 4 Lv80s with full gears and my 5th one is halfway through. So yes, it can get pretty addictive