I guess it depends what you want from a campsite. We went here two years ago, taking our own tent and booking direct with site, so cheaper than Canvas/Eurocamp. We also went in the last 2 weeks of August, so the prices drop (esp in the second week). It was a lovely site, beautiful setting, quiet and peaceful, but had the benefit of shop, pizza takeaway etc (although we didn't try the restaurant; it's very much a Dutch site, so catered more towards them). There was a kids club, but very low-key (ours didn't use it) so there was entertainment but you weren't really aware of it (other than one kids session with music at the pool each afternoon), which suited me fine. No noise/music that we could hear in the evenings.
I think my only criticisms would be that the swimming pool would be very crowded in high season; the first week we were there it was pretty busy (it was a Saturday, and I think the last day before a lot of the French went home, so it was really heaving), and very few places to sit if you weren't there early. By contrast in the second week we had it nearly to ourselves. Also, although it claims to have river access (which is does, of a sort) you can't really swim there - there are nicer places to sit by the river a short drive away. The pitch we were on was not 'private' in the way that some campsites are ie. just a couple of small trees to mark it from those either side (whereas some sites have hedges and it's very clearly delineated); again, depends what you want from a campsite, but suited us fine.
It is pretty remote - a good 25-30 min drive to Millau, which is where the nearest big supermarkets are and weekly market (very small supermarket in Nant, but also a small weekly market). You'll also find yourself driving some distance if you're looking for things to do off-site (it's a good hour or more's trek over little winding roads to the Tarn for instance, but the canoeing and views make it worth it!). We also visited some of the Knights Templar villages (La Couvertoirade & Ste Eulalie de Cernon where you can go on the Velorail which is not to be missed!). We thought there was a lot to see in the area (albeit some drive away in some cases), whereas other people we met who had holidayed in Italy the previous year didn't think there was much, so guess it depends on expectations too. Staff were very friendly and helpful and will pre-book activities for you off-site.
My ideal for a camping holiday is a quiet site with a nice pool (pref with slides for the dcs), some company/other kids for the dcs, good weather, a nice tree I can sit under to read a book, and a few things to see in the area (French markets included); in that respect, Val de Cantobre ticked all the boxes and I would happily go there again.