It's always better than plaintext HTTP. Nothing is worse than plaintext.
TLSv1.2 with good ciphersuites using ECDHE with a named curve like secp256r1 [murky origins I know, but we know of nothing else wrong with it, though Curve25519 is superior in my opinion], and an AEAD like AES-128-GCM or CHACHA20-POLY1305, properly implemented with no TLS compression at least comprehensively prevents Eve from spying on the contents of your connection in most cases, even if you're using self-signed certificates with no pinning and are entirely unprotected from Mallory.
A browser shouldn't call it secure or the endpoint trusted, but it should transparently replace all uses of unencrypted HTTP worldwide, including internal ones. That should not be discouraged, and will hopefully be actioned with HTTP/2 - that was the plan, anyway.
Even if the encryption is crap (Export ciphers... RC4?) I guess it does take some more work for Eve, which knocks out a few of the lower-capability adversaries.
Couldn't Mallory just replace the certificate with her own one? The browser would just pop up the same warning. The warning should show some form of a public key fingerprint at least before clicking through "I understand the risk".
TLSv1.2 with good ciphersuites using ECDHE with a named curve like secp256r1 [murky origins I know, but we know of nothing else wrong with it, though Curve25519 is superior in my opinion], and an AEAD like AES-128-GCM or CHACHA20-POLY1305, properly implemented with no TLS compression at least comprehensively prevents Eve from spying on the contents of your connection in most cases, even if you're using self-signed certificates with no pinning and are entirely unprotected from Mallory.
A browser shouldn't call it secure or the endpoint trusted, but it should transparently replace all uses of unencrypted HTTP worldwide, including internal ones. That should not be discouraged, and will hopefully be actioned with HTTP/2 - that was the plan, anyway.
Even if the encryption is crap (Export ciphers... RC4?) I guess it does take some more work for Eve, which knocks out a few of the lower-capability adversaries.