Unfortunately "good" is in the eye of the beholder. On a general basis? No, they all suck pretty bad, the free ones that is. Much like anti-virus, you get what you pay for. *COUGHAVGSUCKSCOUGH*
Here is a short list of FTP MMORPGs:
2Moons
9Dragons
Heroes Online
Fiesta
Free Realms
RuneScape
Secrets Of The Solstice.
Maple Story. (Thanks for reminding me on the name)
All in all, like I said, you get what you pay for, but for free, these aren't too horrid.