Currently I am on Blyk. What can I say, they have gone from "pretty good", to "absolutely cr*p". Why? Because when I first signed up to Blyk, I was getting 43 mins and 217 texts. However, they have recently changed that to £15 credit, which can be used how you like. Now you might think that's good, but a text costs 8p, and calls are 24p/min. So you can have 187 texts and 0 mins, or 62 mins and 0 texts [or a mixture of both]. As you can see, £15 is a LOT less [almost half] of what it costs to get exactly what we used to get- this would cost £27.68 [for 217 texts and 43 mins].
Fair enough Blyk is still free, but I would certainly NOT use it for my MAIN mobile. Currently it is, but by August end/early September I will get a paid contract, because this company is run by a bunch of cheating, lying people who are completely ungrateful to its customers. Yes it is free for the end user, but this company is making money via the ads and the people that top-up, it is NOT a charity! [Note: I said cheating, because as a "monthly top-up", my refill date seems to increase month on month, from the 13th, to 14th, to 15th etc etc, so they are stealing an extra day like that!]
If you see on the Blyk forums, you will see a lot of discontent by users, but Blyk really don't care. They just said once, that "due to the economic situation we are having to cut back". While that maybe fair, it isn't to the people that signed up when they were offering much more for "free" [via advertising]. So all these people moved to Blyk as their main mobile, and spent money via top-ups, and are now worse off as a result of doing so.
I will keep Blyk as a secondary mobile, but nothing more. Another reason for this, is the numerous problems that Blyk have. I had a problem where I couldn't send texts to certain mobile numbers! Others have problems where they don't get their free monthly refill/their top-up doesn't register.
Blyk, a great idea, which got screwed by the economic climate and it's rubbish "customer service."
Hope that helps you!