For me, it's a toss-up. I rarely play the game now and I havent beaten the 3DS version yet. I got Dragons Peak yesterday and haven't played it yet. I haven't beat all the other expansion levels either (I think i beat 2). I have 31 Skylanders so far (with another free one coming from walmart) and still plan to get Warnado Camo and Lightning Rod (because theyre on my list of favorites).
I have no idea how much i've spent but it has to be in the range of 400 or 500 because I have Console and 3DS and almost every figure. I'm not sure if I really feel it was worth it, but when Giants comes out and I can start the game with over 32 characters to choose from I might feel like I hit the jackpot. The game also supplied numerous hours of bonding time for me and my girlfriend. I convinced her dad to get her Skylanders for PS3

The online play also makes me feel like I got a better deal. Online games are usually free but usually cost a lot of money for full content. The fact that I have all these characters I can use online and unlock new things with and just play fun little games increases the value a bit, though I hope they add a LOT more to the online universe. It's lacking a lot right now.
So after all the money you (or your parents) spent, do you think it was all worth it?