Well if PSN offered a non-buggy multi-player experience I would consider it. I really think that has been a major issue with PSN. Almost every big title has mention of it. The Multi-player works great on XBL but there are bugs on PSN for weeks. If there was some assurance that paying the $50 a year would fix that, I think they would have major sign-up rates.
Only problem with it is that if you purchase a PSN+ download, you lose the right to use the software once your subscription ends.
As it is without it - you can play the game as much as you want, and then re-download it at a later time through the links in the psn-store. With psn+, you lose the game when your subscription expires (it becomes invalidated on your ps3 automatically). And you can't download it from the store again. Which is hilarious, since most of the psn+ titles have a very small price-cut - and the non-promoted titles have no bonus at all.
Of course - the psn-store doesn't actually inform you of this when you buy a title. Instead it only focuses on the small price-cut. Misleading at best, basically. For those of us who don't actually get a movie-service along with the subscription (this is most of the world) - it's definitively not worth it. If you take a look at how many titles you actually need to buy in order to save back the subscription as well, you're ending up with a very high number. Much higher than what even very eager buyers will purchase.
What's the word I'm looking for here again.. "fraud"?