I switched to them few days ago, some feedback for those interested.
Same coverage as O2 obviously, not a problem so far, use internet radio while walking and it streams fine. I cannot text one number on the Meteor network, refuses to deliver any message to them, find that annoying. They wont take laser card for tops, so have to use visa online.... but if they stay this good, price wise.... it's an amazing offer.
I topped up 20 - got 20 extra free, signed up to 30 price plan (leaving a balance of 10) for unlimited (10,000 minutes/ unlimited texts) and "unlimited" data. When you consider what O2 (which Lyca mobile operate on)for the same SIM free plan, you can see how those other networks are really ripping us off... I get that these might be introductory offers and they have no subsided phones to include in the plan... but still...
Customer service seemed very friendly, obviously abroad somewhere and reading from a script, but I fear if I had a complex problem I would get little resolution (speculation)