Like with anything else, I guess it depends

I've been using the free version of TripIt for a while (2 years maybe -- 1.5 at least) and was given a chance to buy a subscription to Pro at $49, which I did.

In my case, I'm often co-ordinating a trip with lots of people -- everybody buys their own tickets but we travel together on the ground. TripIt has been great for keeping track of that and TripIt Pro gives me email alerts when somebodies flight is late/canceled. Yes, I could get that info from the airlines websites, but I find its easier just to get an email rather than having to check.

So, for me it is worth $50 -- is it worth $70? That is probably the max I'd pay, and I might not even go that high.