In my opinion, it's horrible. I didn't buy it, and I still think it's a poor investment.
How do you have the opinion that it's horrible if you didn't buy it and haven't played?
Regarding special seeds, I don't think EA necessarily forgot to put in seed spawners. Instead of finding special seeds around the town, you can harvest the actual fruit (flame fruit, lifefruit) in a couple of places. Special seeds also turn up while fishing quite a bit. It seemed to me that they came from fishing more often than they do in other towns.
But is Barnacle Bay worth getting? Yes, if you want a new town that has new townie Sims, new houses, and a new feel. It delivers all of that. If you want new game play or special features, then no, it's not going to give that to you.