It is still happening, though not as bad as it was. It is now a case of annoying occasional drop-outs and pixelation, rather than completely unwatchable. Examples: last Friday's BBC Prom on BBC4 HD, and the Italian GP yesterday on Ch.4 HD.
I'm finding it better to watch things on catch-up services than live TV these days!
I'm so sorry for the problems you're experiencing with your TV picture, there are no general or nationwide issues regarding pixellation with all channels at the moment so if you're experiencing issues, create your own post and we'll take a look at this individually to get this resolved ASAP.
Apologies again for the inconvenience caused, we're looking forward to hearing from you