Pros - pool area was genuinely lovely during a heatwave. Great food served to your deckchairs. Rooms have great air con, reception staff are helpful (booking us an airport taxi and fixing a bathroom leak issue very quickly). None of the facilities (gym, pool etc) were ever overcrowded, which is a big plus.
Cons - picked the area for the local beaches, but they weren't very nice, so staying closer to Marseille port is probably a good idea if you're not worried about having a pool. Food, although genuinely delicious, was overpriced - €25 for a salad! The same goes for the spa treatment. The rooms were fine, barring two really irritating issues: 1) the shower heads are very badly designed and fall off their stand when turned on, so we ended up having to take a bath each night. 2) our double bed was just two twin beds joined together, but because they weren't designed to be connected they kept on slipping apart at night, which led to plenty of mishaps.
Overall, we had a decent stay there, but there are some very fixable issues that could make the hotel really great. That said, looking at some of the problems of the others in this price bracket, I still think this is the best option for a poolside holiday retreat in Marseille.