I don't like slot loading CD/DVD drives. Too easy to get something stuck, and there is little to no way to remove it without a complete dissassembly of the laptop, and perhaps the drive. Yes, slot loading drives are sleeker and cooler to insert/eject media, but one dvd with a thick label may completely ruin it.
Tray loading may seem a little more cumbersome, but I can put in the DVR mini disks, or other oddball shaped disks and not worry. If something gets stuck, a paperclip will fix the issue.