Ok, I'm hooked. I tried it on a production machine, which, other than a reboot, went very easy and clean. I might be imagining it, but it SEEMS like it's running a little leaner and lighter.
One nice thing I was looking forward to in 5.3 was the addition of support for cmirror. Cmirror is a script to mirror a single directory from an FTP site to a local directory. It can also mirror a number of directories. It uses NCFTP as its engine. This was previously an "add-on" but without full kernel support it wasn't as great as it was being billed. I'm hoping to see some great things come out of cmirror and ways in which we can integrate it with Directadmin based servers.
NEdit, a cross platform text editor/markup editor is also a rather cool enhancement.
While I'm not 100% convinced of it's readiness for prime time compatibility with DA, so far, so good.