I use a combo of SplashMoney and Yodlee. Yodlee and Pageonce are very similar, except that Yodlee is free.
Splash is similar to Ascendo (direct competitor).
So, to answer your question, to me, they are complimentary. I use SplashMoney as a COMPLETE financial/check register. Yodlee is used to keep up with all accounts online.
I used PageOnce for the iPhone (it was free) but had some issues with it not being able to access some of my accounts.
I deleted it.
They claim extreme security, I wasn't so convinced.
It's not something I'd pay for for sure.