I've posted my thoughts on the leveling speed on the thread I linked above, but in a nutshell I think it is important for it to be the old pace. Bare in mind, this is Shrouded Isles exp rate, with which you are able to level 1-50 in a group within around 30-40 hours /played (ymmv) on average, but can get there within ~20-25 hours /played if you have solid knowledge of the game, likely even faster with past experience, I'm curious how long it will take me
Much of it is certainly nostalgia, but even looking beyond that the leveling pace and method of leveling faster very much encourages group play, which in turn requires you to be social (at least to a point), I met people I'm still in contact with today in such groups despite it being 13 (!) years later, and found it quite similar on the old Uthgard (which I only played for a few months, but still).
It's also not really logical to think "exping takes too long, won't play" because either way, you will spend an infinite amount more time on your character in RvR than you will do leveling, at least if you intend to play for a decent amount of time, which I imagine most old players are hoping for.
For people who will be playing DAoC for the first time, know there will be a lot to learn and a handful of old mechanics in play that aren't all that similar to the MMO's of today, and you'll likely find movement to be clunky until you get used to it. If the idea of complexity and learning something new intrigues you, you'll have a great time, if it doesn't then I'm not so sure. But as someone else mentioned, Uthgard is free so no harm in trying it out.
Regarding Camelot Unchained, who can really know how it'll turn out. Personally I hope the game is close to what made DAoC so magical and have so much longevity, but I doubt this will be the case given any MMO since DAoC's record, especially with Mark Jacobs. At least he has shown good ideaology so far and admits his past mistakes.
I personally can't wait to start on this server once it launches - I've been waiting for a long time for such a "reset", never thought it would happen really. I'm extremely curious to see how the experience will differ given having extensive knowledge from playing in the past yet returning to those times. Currently only plan to level 1-30ish during the Beta, but that may change depending on what needs testing etc etc.
Anyhow, 34 hours until I hear this soundtrack <3
http://www.etaew.net/daocdb/sounds.php?play=humberton.mp3