I was like you once. "Playstation Plus, is it really worth it?"
Yes. Yes it is. Without question. If you don't have plus and play games on a regular basis, then I...well, that makes me very sad. I just got it in October when they were having a "Spend $50 get $10 back". Its paid for itself and then some.
They offer at least 5 games a month, 3 ps3 games, 1 PS vita/PSN/PSP game, and now one PS4 game. Sadly, you won't be able to get access to previous free games (for example, if you join now you won't be able to get Dragons Dogma dark arisen, as that has come and gone). However, games that you DO get stay with you forever as long as you are still a member of PS+. So if you get Bioshock Infinite, your subscription runs out, you won't be able to play Infinite until you become a member again. Once you do, you'll have access to it again. Depending if you live in the US or UK, the offer of games will be different to some extent. Once you download a game, you can always redownload it again later with no problems (as long as you are a member of course), even if it isn't a free plus game anymore. Again, using Infinite as an example: If you download it now as a member, say you delete it in order to get a different game. You can easily download it again, even if it is no longer being offered as a free game.
The games have been quite worth it though. Many were games I wanted to try, but didn't have the money. Then you have stuff like Bioshock Infinite that came out almost a year ago being offered already. Forgetting the fact if the games are good or not (though from my experience, they have always been at least decent), getting games that constantly exceed the amount you pay for plus is good enough for me. The range of the games vary (Infinite sold quite well, while I don't think Remember Me did).
Not only that, but you have the very good deals from the Playstation store. Games are constantly discounted, and plus members usually get even MORE of a discount. I've purchased at least 7 $15 games, all of them being less than $4. And unlike the free games given to you by plus, these I keep no matter what. Example, say you buy Limbo at a discounted price and your subscription ends. You are still able to play Limbo to your heart's content without any problems. It really is amazing to get games like Tales of Xillia, Puppeteer, and Ni No Kuni all less than $10. PS+ makes even more sense if you have a Vita. I have at least 10 Vita games or games I can play on the vita, and I've only been a member for just 4 months. Granted I don't OWN a Vita yet...but I hope to change that!
Really, Playstation plus is extremely worth it. The only problems would be that you can quickly build up a backlog of games to play (especially with the discounts), and that they might offer games that you already have, making that particular month feel pretty meh. I think plus is worth it even more if you're someone who really only gets maybe a few set games a year, the ones that you are really dying for. I feel Plus loses its value if you are someone who is buying almost every new release that is available, as you are bound to run into those game being free.
The Cloud saving is nice I suppose, mostly in the case of your PS3 just breaking down for some reason or your files getting lost or something. The ability to have the system update at whatever time you set it for is nice too, especially if you live with a family that constantly hogs up everything internet related during the day.
So...hopefully that was all helpful and didn't sound too confusing. Lol.
EDIT: Oh! Completely forgot another negative: the Hard Drive space. I only have the 80GB version, so I can't constantly be downloading every free game that comes my way. Make sure you have adequate space available! Games always require at least double the necessary space (EX: A 6GB game require 12GB of space). Keep that in mind!
