TalkTalk user here.
Never had any major outages in 3 years with them and speed was as advertised, DNS can be a bit flakey but I tend to use a combination of OpenDNS/GoogleDNS anyway so that's a non issue for me.
CS is overseas based but the UK based members forums are actually pretty good if you have a more technical issue than clearing out your browser history.
Recently swapped to there Fibre Large package and get 54 down 14 up, strangely I was able to order fibre with them and have it up and running a month before BT said it was available in my area.
I get no issues with speed and a very stable connection, I have never noticed any issues with throttling or had poor ping times in games. The router supplied isnt great for options or WiFi (but neither is the SuperHub from Virgin or the Hub from BT) so I just swapped it out for the Asus N66U and everything is peachy.
Nothing wrong with my connection TT Fibre (I believe all fibre except Virgin is just resold BT products)