@MrBoat has similar speakers, maybe he can comment....
THe JBL S312? Love those speakers. In spite of what many conclude about superior bass performance from separate sub-woofers, I have to place them pretty much inconveniently to rival a good 3-way in my rooms. The mic and sub crawl prescribes that I use one as an ottoman, and the other by my hallway, right in the way. I had to move them into position every time I want to listen critically, which is most days. Otherwise, they have to be up on the front wall where my main speakers are to be out of the way, in the space the rest of my gear is in. When I get tired of messing around, I put the JBLs up front and forget about such things for awhile.
William is right. Most competitively priced options are a lateral move. In some ways I suspect the S312 are still better options if one is firmly rooted in say, classic rock, or mainstream pop/country music. Some of the newer speakers are too revealing for their own good.
Then again, I am a music only listener. But I cannot imagine the S312 not being enough for movies. Honestly, if I had not happened upon the internet audio scene, I would have never wanted for anything else. After a few years messing around, building quite a few kits by now, I still hold the same conclusion. Also hard to forget, I only paid $75 for a well kept pair. JBL has done well with their polyplas drivers for a long time.
What puts people off about the S312 and the 590? They don't cost enough. They can't belong to the trendy hi-fi circles online, unless they drop $10k or more on a set of towers. I have heard more expensive speakers. My conclusion was that most are colored to what we 'hoped' music would sound like, more than what it really does sound like.