I've checked my Personal Capital account rarely on and off, but check Mint much more often. Part of that is the simple reason that we were using Mint first, so it is already set up and we've invested in editing transactions manually.
I do sometimes find Personal Captial is better at classifying some transactions automatically as opposed to Mint. IMO, where Personal Capital really shines compared to Mint is in tracking your investments and giving you different kinds of information (asset allocation, performance over time, etc). So if you like looking at different charts of your investment return, it can be kind of fun. I don't know how practical it is, but perhaps for someone with a complicated portfolio across many accounts it would be useful. I do generally find Mint better for keeping track of household expenses, etc, but it is weak on the investments side. I am sure they are targeting different niches.
If anyone is interested, I have a referral link for Personal Capital:
http://refer.personalcapital.com/a/clk/476GTF If you sign up through that link and link an account, they send you $10 via Paypal (disclaimer, I also get it if you use that link, I hope referral links are allowed). I suppose as long as start-ups are chasing users, there will be referral money to throw around.
