We went the last week of November last year! We were a little worried because most reviews we read weren't so glowing...but we had a great time. We found the people friendly and helpful (many reviews refer to rude resort employees--not our experience).
The setting is fabulous--sugar-white sand, and glorious water. While we were there we had "Aruba weather" with warm sun and constant breezes. It was heaven! There are some vendors that will annoy you on the beach, usually in the morning, but after a while they stop bothering you. The resort provides free lounges at the beach. The beach was very uncrowded, but while we were there many of the nearby buildings were still closed down from the previous hurricanes so I don't know if that will still be the case.
The resort had very few sponsored activities, and it is sort of in the middle of nowhere. They do, however, have a shuttle that will take you into the small tourist area (I can't remember the name) where you can do a little shopping and visit many nice restaurants. If you want to rent a car be aware that they drive on the "wrong" side of the road

You can negotiate with taxi and bus drivers, and ask around the resort for anyone who wants to hire out their services as a driver. One fellow there, Mitch, seemed to do a lot of this.
We had a 2-br with a fabulous view over the pool and ocean. Daily maid service was a nice bonus! The air conditioning is done with individual units in the various rooms, not a central system. There is an on-site washer and dryer building that is free to use, but no in-unit washer/dryer.
We really were in the mood for a laid-back relaxing vacation and that is what we got at the Island Seas. The only night-time activity we tried was a weekly "fish fry" where you could get all sorts of seafood, and some bars were open and appeared to be really hopping.
There is a bar in the center of the resort complex where they have a daily happy hour (be careful, not all drinks are offered for happy hour), and they also serve food. We only ate there twice--once for lunch, and once for a special buffet dinner they put on as a resort activity. Food was okay, not great, but not bad, I would rate it expensive for what you get. They have a very tiny convenience store, very expensive and extremely limited selection--but food is also much more expensive in the Winn-Dixie than we are accustomed to at home. They import everything and the cost reflects it. The only other meal option within walking distance was Zonk's Conch shack a short distance down the beach--I liked it, but my traveling companions didn't. We ate all breakfasts and most lunches in the unit, and had dinner out at the tourist district a couple of times (Greek restaurant where the owner is a Steelers fan was good and very reasonably priced). We only made one grocery shopping trip the whole week--we took the Island Seas shuttle into the tourist area, and from there hopped on a "public bus" (which is a van) to the Winn-Dixie. We could've done the same thing going back but a taxi driver offered us a great rate to take us back to the Island Seas with our bags. The public bus driver gave us her card and said she would come pick us up, and drop us off at the end of the Island Seas street (not a scheduled stop) which would have been a good option too.
We were able to use US money everywhere. Everyone spoke English.
I would definitely go back!