I know for myself, dual-boxing renewed my interest in the game - I was ready to quit and move on, but I saw the battlechest at BestBuy, and on whim gave it a try.

I'm hooked.

My vote is it's completely worth it, every cent and ounce of effort. It opens many doors to you, in terms of what you can do, and it makes it a whole new game. I was utterly burned out on the post-70 game: I burned out on raiding, so i got into PvP. Did that for months, got a full - and I mean full - S1 set, fought every match, gemmed and geared my toon out, got pretty good at it, too. I started going for S3 and Arenas, and got disgusted with the blatant cheating and attitudes of the Arena crowd. Did'nt have the fortitude to level alts solo. I was logging in less and less, and felt like I was falling further and further behind, because like everyone else, I was basing "fun" on gear and rep and epics, and the race to grind out honor and marks.

Meh.

Now, i play for ME. I level as fast as I want, and if I take a night off, I don't get that "I'm losing gold/honor/marks!" feeling. I can handle most quests, and my goal is to solo 5 man quests all the way through Outlands, someday. If I don't make it, whatever, it's cool. I have FUN. I log off when I want, not when the raid is over, not when I have enough gold or honor or whatever. Quest half done? I'll get to it tomorrow. Or the day after. I'm learning how ALL the classes work, and how classes work together. I'm doing ALL the quests, and boy, did I miss out on a lot leveling my main!

Worth it? I can't imagine not doing it, now. It made the game better in ways you can only discover by doing it.