I have RCBS' hand priming tool. It's OK, but having to (basically) disassemble it to change calibers/primer sizes (or if you only have one shellholder to share between your press and priming tool per caliber) is annoying. Also, the circular primer flip-tray is smaller than most boxes of 100 primers, which means I can usually only dump primers into the tray 10 at a time.
On the plus side, if I'm reloading a lot of one caliber (in my case, either .38 Special or .45ACP) it's a lot faster to leave the priming tool set up for that caliber (I have a second shellholder) and not have to worry about loading primer tubes for my RCBS bench-mounted priming tool (or the priming system on my Rockchucker).
If I could do it all over again, I'd look into RCBS' Universal hand priming tool. No need to disassemble to change calibers/primer sizes, and the square tray looks to be as big as most 100-pc primer boxes.