I'm going to go against the grain here but after subscribing to EU PS Plus for the last 6 months I've cancelled my subscription now.
PS Plus games tend to fall into one of the following categories for me:
1. Games I already own.
2. Games I couldn't give a shit about playing.
3. Games too big for my 40GB HDD.
4. Vita games.
Over the last 6 months the only games I got out of it were Quantum Conundrum and Thomas Was Alone.
PS Plus is fantastic for people who for some reason don't buy highly acclaimed AAA games within 12 months of launch, which I tend to do. Most of the time if I'm interested in playing a game I will have already bought it before it appears on PS Plus.
A lot of PS Plus games are genres I don't care about, such as beat-'em-ups. If I've passed on a game it's usually because I've deemed it not worthy of my time so it going 'free' isn't going to change that.
I wanted to get Vanquish, Mass Effect 3 and Hitman Absolution but they are far, far too large for my 40GB HDD and I feel it's too late in the gen to upgrade now.
Also I've got to say PS Plus was better when they gave you four PS3 games a month, but since extending it to Vita it tends to be just two PS3 games and also two Vita games, which is great for Vita owners of which I am not one.
Finally, I don't like the fact that it's essentially a rental service. When you one day unsubscribe to PS Plus all you are left with is your rapidly fading memories and a lighter wallet. I like to own products. I've never rented or sold a game in my life, I still have a bookshelf full of all my PS1 and PS2 games. People hated the idea that one day the Xbox One DRM servers could be turned off and they would lose access to their games but PS Plus is the same.