I'm on UK Online's 24mbps service (not available to new customers, sorry!) and am very happy with it. I SYNC at 22.5mbps average, and see about 20mbps to 21mbps in throughput, solid. No peak time slow down, and no caps to speak of (though I believe they can get antsy if you keep downloading more than 500 GB a month - tho' a mate has downloaded a TB a month and not had trouble lol).
Tech support isn't up to ADSL24 standards, but it's decent enough. Level 1 are script monkeys, but polite and happy to hand you straight up a level or two if the situation demands it. Think of them as receptionists lol
Level 2 is decent for what it is, they can diagnose and sort most network issues quickly and without fuss. Just don't expect them to tweak your line much - they've been known to carry out requests (such as lowering impulse/interleave depth) but not do it correctly. I had them change my DELAY instead of the DEPTH, and they refused to carry out any more changes after that (not even back to how it was). Luckily my line is still solid.
Some folks on another forum have had their line so badly messed up they lost between 5 and 10mbps SYNC and UKO refused to fix it, giving the "we can't tweak your line any more than it is - it's as good as it'll go". When asked how it's as good as it can be, when it's 10mbps down on yesterday, they get quite cagey lol
That said if you have a decent line, and know how to adjust SNR etc yourself, you can't really go wrong. I've had them for three months now and my speeds are blistering. I'd rather go with Be* if offered, I think, but no complaints either way
