I joined my friends from Wow on a legacy server and these are my observations so far :

Lots and lots of people running around on Gobbies (sp) or other mounts but I'll be able to get mounts soon too. Mounts make a difference in fate grinding - if people can get to FATES quicker, they end quicker.

The Market Boards looked rather stupid. I prefer to have as little reliance as necessary on others but the few items I looked at were insanely priced (ie 10,000 gil + for lvl 10ish items). That may have just been a function of it being Beta and not many people using the boards but there it is.

For content, I am looking forward to doing endgame stuff and having not to find a group from scratch will be helpful in that regard imo. ie it would take 8 people longer to get to 50 than it would the group of us where some are ahead.

So pros and cons really...