Are there any catches/gotcha's with UK 3's 200mb/month free in Europe?

TL;DR On the whole, the answer seems to largely be "No once you've registered it". Mine has worked fine for free data in the UK and in Sweden

Having got one, and had a play, the biggest problem I hit was when trying to register it. It didn't matter what I put the sim card into (Android phone, old Nokia phone, tablet etc), whenever I tried going to www.three.co.uk/freedata to register, it'd pop up an error page saying

First, make sure you're connected to our network. Then we can check that you've got a compatible SIM and get you online. Just turn off Wi-Fi in your device settings and then refresh this page.

Eventually, based on some hints on other forums and a bit of trial and error, I worked out what was going on. It seems that Three UK have two different APNs, and the sim only had the "normal" one baked into it three.co.uk . Manually adding the other one 3internet and connecting with that allowed me to get the www.three.co.uk/freedata page to load so I could register

Since then, it doesn't appear to matter which APN I connect to in terms of using the free data. It does matter for if you'll get an error about tethering (which is odd since it's officially marketed as being suitable for tethering via a USB stick or their MiFi wifi sharing device!) - needs to be on 3internet to avoid the problems.

Otherwise, the 3 Android app (normally used for seeing your remaining usage, topping up etc) doesn't seem to work, so you seem to need to do that using the normal website.

Oh, but one thing to make clear - this sim is data only. You can't use it for calls or texts. If you're after a cheap sim for calls+data, you either want to get a normal 3 UK PAYG sim (can get 120mb of data for 1-2 days for 50p, 1p/mb when in the UK, 150mb free every £5 topup), or get a free phone sim from FreedomPop which also has 200mb/month free plus cheap calls.

TODO: Things I still need to test out:

• Does a £5 online topup get 150mb free (valid 30 days) like it does for normal PAYG 3 sims?
• Is the "Internet Daily" add-on (50p/£0.50 for 120mb valid until about midnight the next day) available, or just the more expensive monthly ones?
• Does tethering from a phone work when in a "feel at home" country, or do they block it?

Yes, there's a gotcha: 3 UK "Feel at home" countries will only make you feel at home if you have dial-up at home (I actually remember browsing the Internet when the whole country had 64 kbit/s to abroad and I had a 14.4 kbps modem). That's maybe an exaggeration but it's very severely throttled. There are various blog posts corroborating this but I just had first hand experience with this in Italy, France, Switzerland and Ireland.

calls and texts on this data sim are ALLOWED - priced as per 3's regular payg 321 plan, just no voicemail - hello Hullomail

Just buy a 'international credit' on the full desktop My3 version not the mobile browser, instead of a £/GB add on.

This is easy to do as using 3internet as the APN as it will send you there instead of the My3 mobile site, go to My 3/account, login (and you already will be)

Mobile Broadband Price Guide - page 5 onwards states add ons & then call charges as 3p calls, 2p texts and 1p per MB http://www.three.co.uk/Three_price_guide

The free Data & add on data bundles can be used roaming in 42 Three Feel @ Home countries http://www.three.co.uk/Discover/Phones/Feel_At_Home