I've dabbled with an MMO here and there but never got one to stick. That said, I've been very curious about Guild Wars 2, especially since it doesn't have those silly subscription fees attached to it. So right now it's on a half off sale from Arena.Net's site and I was wondering whether it would be worth it? Also, is there a good way to solo when not trying to team up?

I'd recommend it at that price. I bought it on sale for $30 a little under a year ago, and I really enjoyed it.

In fairness I should say I play a fair amount with people I know outside the game, and that may color my perception of it somewhat. I feel like MMOs appeal to me a lot less if I'm not playing them with people I know in some other context. But, I do feel it's still a pretty fun game in its own right.

Very little in the game requires a group -- basically dungeons and fractals (which are essentially another version of dungeons at endgame). The outside PVE world and the personal story can be completely done solo, and the small-scale team PVP and the large World Vs World PVP, though team-based by nature, can both be entered as an individual.

I have only played the first Guild War, but it was a ton of fun. If it is like number one, you can get a number of NPC's to join up with you to go through the various scenarios. They are often the same NPC characters, but leveled up as the difficulty increases. It will provide you with plenty of fun for 25 bucks.

Ehh... GW2 doesn't really have that.
There are summonable minions and such, and there are NPCs you might be allied with in certain places, but this game doesn't have a hireable hero/mercenary system that I understand the first game had.

a couple of friend of mine suggest no when im asking if is worth it month ago (roughly same price 25 $) ,they say the content quite stale and booring. my friend and i usually dont mind with grind in every game, and when they say they are boored only after 3-4 month i guess i knew the answer

I love the first one. Never got the second; I remember reading all about it and not liking what they changed.