I joined about 2 years ago and spent about a half hour trying to use it. Soon afterward I got my 60CSx and never went back to the website. I still get an email now and then, but I get tremendous volume of spam and just deleat it without hesitation.
Very recently I have done a lot with wikiloc. It allows you to post GPS tracks, GPS waypoints, and photographs. The above can be viewed in Google Earth. GPS data posted by others can be downloaded onto my GPS. I think it is the best thing going.
I've considered joining trails.com, but noticed much of the info is available online or through word of mouth. Figured, if I ever get tired of researching new hikes for upcoming weeks, (right now I think it's half the fun), I'll join up.
The downside of joining up maybe the bill and the increase in spam I guess.
I signed up for a trial run when I was planning a trip to Zion. Then I noticed that their info was taken from a very few books. I figured it was cheaper to buy the books - and nicer than having lots of loose paper (I am not a very organized person).