Plusnet FTTC currently works very well for me. Telephone support call queue times are quite an issue currently but that's only a problem if you need to use telephone support and somewhat dependent on what time you call in. Online chat support is better than telephone in terms of waiting time but not perfect. On occasions when I have had to use support I have found the actual support quality good. The Plusnet forums are excellent for informal/community support. I don't think Plusnet have any current issues with their own network (congestion / speeds / throttling), some users occasionally suffer from local exchange issues - I guess that could apply to any ISP.
Overall I'd recommend, particularly if cost saving is important.
I currently use Unlimited Fibre (I'm on the old 40/20 so I enjoy much better upload than the current 40/2 which might be an issue for some), the 80/20 Unlimited Fibre Extra should be comparable with BT Infinity 2 (you might loose ~2% download throughput speed due to Plusnet's 'line profile' system), I also use Plusnet for line rental (I used to have this elsewhere to save money but I also now use their TV service and they will only supply that if you use their line rental as well as FTTC), I don't have a calls package as all my outgoing calls are via VOIP with minimal cost, I only use the TV service so my kids can get Disney / Cartoon Network etc. without paying ridiculous Sky TV prices.