That’s $17 per month for a 4 people server (with the $25 plan, $15 per month with the $45 plan). I don’t think that’s a competitive price (but don’t quote me on that, I have zero experience setting up or shopping for Minecraft servers). They also don’t support any plugins. It, however, looks like the service is incredibly easy to set up and use.
Just like with Dropbox, you pay more but you (are supposed to get) ease of use in return. I think that can work if done correctly. (There are also other advantages: You don’t need one gracious person to set up everything and pay, you don’t need to collect donations, …)
Edit: Wow, the experience really is smooth. It took me not much more than a minute from their homepage to running around in my own multiplayer world. I have never set up any Minecraft server anywhere and zero experience with all of that. Nice work!
Yep. It's a bit of a change from what people are used to be we think it makes more sense. It means you personally can stop playing and you don't have to keep on paying for your friends. It also saves all the hassle of collecting donations to run a server.
We are, however, working on let you "shout" friends.