It was about a month ago that Gamefly announced a new game streaming service. Last week I got an invite and was happy to finally have something to use my Amazon Fire TV game controller with (Gamefly's streaming only works on the Fire TV for now) so I took it for a test drive.
You get started by downloading an app to your Fire TV. Running that app brings up the Gamefly streaming interface. There were 26 games available when I tested the service. You can try any of them for free for ten minutes. If you find something you enjoy you can 'rent' them in packs of 7-16 games for $7-$10/month. I couldn't find a way to rent a single game and there is no permanent purchase option.
The trial period is the first problem with the service. A ten minute trial sounds OK until you consider that these are full games, and come with all the upfront overhead of a full game. You'll get the intro videos and all of that, and the time these features take up cut into your trial. For example I tested the game Dirt 3 (an offroad racing game) and clicked through all the screens as quickly as possible and my timer was down to 7 minutes by the time I got to my first race. That left me enough time for one full race and part of a second.
It's not terrible but it doesn't show a lot of confidence in the games. A 30 minute trial period would feel more reasonable; you'd feel less pressure to click past tutorial tips and the like as quickly as possible. (As a random comparison the Xbox One's new Preview Program gives you a 1 hour trial before buying the games.)
As for the streaming experience itself, it was just OK. Now a streaming game experience can vary a lot from household to household and even day to day. I tested it on a 30 MBPS down, 5 MBPS up connection. My Fire TV has a wired connection so Wifi issues didn't factor into my tests. The app reported that I was connecting to a data center in Virginia (I'm in North Carolina) with a 720P, 8 MBSP connection.
The racing games I played were most problematic, with the display breaking up a little and there being just enough lag to make the cars really hard to control (I own Dirt 3 on PC so could compare streaming controls to local controls). An action game (Darkstalkers) worked a lot better. I suppose there's less data to transfer in a game where you're not constantly moving. Even in Darkstalkers I had some brief audio issues and the like; the game was definitely playable, but you'd never confuse it with playing a local copy.
My recommendation is that if you already own a Fire TV and the game controller (the FAQ says an Xbox 360 controller will work, too), it's worth testing the service to see how well it works for you, but I wouldn't purchase a Fire TV in order to get access to Gamefly streaming. In my opinion the experience isn't good enough to justify the hardware purchase, and frankly most of the games on offer are pretty old. Hopefuly Gamefly will start adding more recent titles and improve on their infrastructure over time.