It's not small print in as much as it's very clearly stated on their website.
I split my time between the UK and Italy, with some work in Hong Kong & the US - therefore it's perfect for me. I don't run over and pay approx £30 a month regardless of travel on a sim only, month by month plan. I do have one of their old sims though which has unlimited everything.
The only point of note I guess is that the internet is a little slow in Italy but then I'm also comparing that to my Italian 4G phone on Wind. Long story short, it's an excellent deal which has played a major part in keeping me retained as a customer.