More fun but definitely not reliable. Twilio interconnects directly with carriers and handles most of the gory details to make sure your texts reach their destination unmolested.
Sending directly from a SIM can have undesired side effects, deliverability issues, mangled text, etc.. and the carrier probably won't be too happy with you "abusing" their service (you'd be surprised how fussy they can be about 160 bytes of data).
Sending directly from a SIM can have undesired side effects, deliverability issues, mangled text, etc.. and the carrier probably won't be too happy with you "abusing" their service (you'd be surprised how fussy they can be about 160 bytes of data).