No.

Practically everyone who knows about or cares about the BIP process loudly yells at people DO NOT USE BRAINWALLETS.  We've seen pretty concrete evidence that users are resistant to good advice in this space, and they are shocked when their favorite quotation is cracked and they lose their coins (But it was 60 characters long! I even added a special character! how is this possible?!),  the existing sites promoting this stuff won't use a KDF stronger than SHA256*1 because "users are stupid if they use weak passwords".


BIP∞: Brainwallets.

FOR GODS SAKE. DON'T DO IT.  YOU MAY THINK YOU ARE SMART ENOUGH. SO DID EVERYONE ELSE WHO GOT ROBBED. HUMANS ARE NOT A GOOD SOURCE OF ENTROPY.

YOU HAVE A SCHEME?  Pfft. THE SPACE OF ALL SCHEMES YOU'RE LIKELY TO HAVE PROBABLY ONLY HAS A FEW BITS OF ENTROPY. RANDOM PHRASE IN A BOOK? THERE ARE ONLY ABOUT 30 BITS OF SENTENCE SELECTION IN A LIBRARY.

OH NO. YOU ARE NOT LISTENING TO ME, ARE YOU?

OH CRAP. YOU THINK THAT "EIGHT CHARACTERS AND ONE FROM EACH CHARACTER CLASS" APPLIES HERE??  WEBSITE SECURITY MIGHT HAVE TO DEAL WITH 1000 ATTEMPTS PER SECOND, BUT SOME DUDE WITH A FPGA FARM IS PROBABLY PRECOMPUTING A BILLION BRAINWALLETS PER SECOND. JUST STOP.

NOOOOOOOOOOOO.

Well, now that you have no more Bitcoin I guess we don't have to worry about you using a brainwallet.

Cheers.


Of course, if by brainwallet you mean a key the user has memorized... it's not hard to memorize 128 bits mnemonic encoded. Though the risk of data loss is kinda sucky: People are really not all that used to data that cannot be recovered if lost.