Doesn't allow texts to short numbers, doesn't state this clearly anywhere, and their customer service is pretty useless. Signal is ok in towns and cities, but absolutely awful if you go into a more rural area. I get a decent signal with both EE and O2 in the same areas Smarty has little/no signal.
When asked about the texting to short numbers I was told "The team are working on it". Turns out they meant to say they aren't working on it and there is no current plan to provide it.