Several threads on here about the poor camping facilities, dirty toilet blocks, rude wardens and inconsiderate campers on many Haven sites. Each to their own and some people on here are happy with them but I personally wouldn't go back to a Haven site.
I've been to several Haven sites and mainly found them to be very good and excellent value for money IF you can go during the week - very expensive at weekends and probably packed out. Never found dirty toilet blocks and rude wardens, but it may well be totally different at weekends.
Not sure about Reighton but we had a UK rally beginning May bank holiday and were very impressed. Not stayed on a Haven before but we had no problems at all, even got a good deal.
We stayed at Reighton Sands this march and found it to be good as the pub and restraunt area had all been refurbished although some building work was going on behind the touring pitches (new golf course i think!) it didnot spoil our stay. Found the staff to be helpful and the shower and toilets to be cleaned regularly ,baring in mind that this was begining of the season. Ihave stayed at other Haven sites peak season and considering how packed they get they are reasonably clean, but some fellow campers leave a lot to be desired by the way they leave the facilities! So go with an open mind and enjoy it