Hi smthkat789,
The industry has changed a lot in the last 15 years and unfortunately it’s not likely that you would see this king of durability from a Simmons mattress sold today (see post #3 here and post #404 here).
I don’t know the specs of the mattress so I can’t make any meaningful comments about the quality of the materials (you would need to find out the information here and post it on the forum) but given where you purchased it and if it’s made by Brooklyn Bedding I would say that the odds are very high that you made a good quality/value purchase.
Congratulations on your new mattress 
Phoenix