I switched to AA after many years with PlusNet. The day I switched, BT decide to upgrade my local exchange to ADSL2+. It took me about a week to realise that it wasn't the switch to AA that gave me a much needed speed boost but the highly coincidental exchange upgrade.

No problems with AA so far. I like the dashboard controls and the ability to monitor usage and line performance - very nice features.

My only gripe is that in an Apple dominated household with iCloud, Photos, iTunes, iPhones, etc, the basic 100GB limit is NOT enough. I'd be happy paying £25pm for a more reasonable 200GB. I would urge AA to seriously consider increasing this, otherwise I may have to switch back to (the now much faster) unlimited PlusNet after my minimum contract period expires.
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Two years later....and after a house move, back with AA again and now on FTTC with a slightly better 150GB monthly limit. The overall value proposition is much better if you take AA's VOIP service taking call costs and line rental into account. Therefore I have increased the value rating from 5 to 9. VOIP is excellent and AA's customer service is as outstanding as ever.
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Now with a new rolling carry-over scheme of ½ of your unused bandwidth. AAISP continues to get better and better.