Here's a quick rundown of everything that Playstation Plus comes with:
Many of you may be saying, "Yeah, so?". For me, this service has my name written all over it. I'm going to leave out what isn't exciting to me and just focus on what makes me want to subscribe.
First off, I'm quite fond of downloadable games. I own about 40 right now compared to a measily 6 for disc games, so discounts on the PS Store, alone, is worth it for me. I've had my PS3 for 2 and a half years, putting me at about 15 games per year. Let's say I spend an average of $8/game, that's $120/year I spend on PSN games. Discounts are to range from 20-50%, so at a minimum I'll save $24/year on PSN games from a $50 subscription. Uh... sweet? Plus, the more games cost, the more I save, and there will be higher discounts that will save money as well. This also applies to the video section of PSN, as well.
The next big feature for me are the full game demos. This is an amazing feature. Demos in their current form are great, but sometimes the limited features and gameplay don't really give you a full sense of the game; making you regret your purchase and then getting slapped in the face when Gamestop offers to buy it back from you for $3 store credit. Being able to demo the FULL game and play it for an hour will give you the best opportunity to decide whether the game is worth buying. Another cool thing about this? Trophies and save data are retained should you decide to buy it later on. Pretty nifty.
Lastly, there's the "free" games. As long as you're a Playstation Plus subscriber, you'll have access to a certain selection of free games every month. So that's "free" as in they come as part of your Playstation Plus subscription. Now, whether or not you'll absolutely love the offered games has yet to be determined, but it seems as though there will be multiple offerings every month so if you like the PS3 enough to pay for premium content, you'll probably fine at least one of the offered games entertaining.
To recap why I'm going to be subscribing: