I like to hop in when they email me once a year or so and offer a $1 month. But, yes, the shipping times are horrendous. I had them send me NFS rivals once for the PS4 about a year ago, and I shipped it back and canceled the service just before my $1 month was up. It took over a week just for them to receive/check the game back in, and they actually billed me for the game. They reversed the charge when they finally checked the game in, but it was ridiculous that it took that long to get to them.
As far as people wondering why the shipping is so slow. companies like Netflix, Gamefly, etc negotiate shipping rates with the postal service. You can get a lower rate by allowing your parcels to be de-prioritised. Part of how they manage to turn a profit is steeply discounted shipping charges. Gamefly has clearly let their shipping costs take a larger priority than they used to, resulting in slower shipping times.
I was really disappointed when Netflix decided not to get into the game rental business a few years back. They would have really been a strong competitor.
All that being said, Gamefly can still be worth it if you aren't paying full price (do the buy a month gift cert/get a month free deal). Only suckers pay retail/full price.
Last, if you want to get the new releases, be sure to have no other games in your queue when it comes time to ship. If you have other games in your queue, you're going to get sent the most readily available, least demanded game. The members with only one game in their queue will wind up getting the new release you're hoping for.