I was migrated from TalkTalk to ICUK on the 22nd of December without any fuss or difficulty, It took about 6 hours or a bit less for BT to get it done. Since then everything has been fine, My router is currently showing 17912 down & 443 up (ADSL2+) which is an improvement on TT's LLU.
The control panel for my account keeps track of everything I need to know, bb usage, calls made with their cost etc.

Early days, but I'm well satisfied so far.

The present ratings I've given are not a very good guide as it's too early to give a considered analysis, so I'll update them in a few weeks time.

6 months or so since I posted the above.
Not a lot to say, & that's a compliment. Sync speed is far better than TT LLU was. Now about 20000kbps, stable connection. Quick response to queries I've made. I was on 20meg monthly limit, but I've found that 10 is ample for my needs. I was able to change it online myself & cut monthly costs by £4. Phone calls are DIRT CHEAP - 1p + VAT for UK & about 1.8p + VAT for USA.
Total cost per month not much more than TT from a far more trustworthy company.

Well worth consideration if you're looking for a new ISP