I moved away from Lyca earlier this year. While their data is OK in general (certainly faster than giffgaff on O2's net, probably on a par with O2 PAYG customers in terms of priority) I was getting fed up with text messages either not getting received by those I sent them to and vice versa (or taking several hours otherwise) plus my phone and other family members' phones were randomly not receiving calls despite full strength signal indication with the phone in the same room as the caller! If it is purely for data they might be worth a shot to see if they work out OK, but if phone calls and/or SMS is in any way important then avoid.