It depends on a number of variables, including how long you've been with DirecTV -- if this is your first two-year contract or not.
Typically, DirecTV makes you pay certain one-time costs for the Genie receiver if you're under two years with a contract. I found this out when they tried up selling me the monthly warranty deal that "allows" a "free" upgrade once every two years. However, if you wait either long enough or call into the right CSR and ask for a deal, they tend to work with you (they did with me).
Regardless, you'll pay a lease fee for each physical device you have (Genie counts as one even with its five tuners). You'll also have to have a SWiM-compatible coax network for it (normally comes with standard installation (Google "SWiM" for more info or search on my previous postings for more). If you go wireless Genie mini (they're fantastic), that counts as a separate receiver per device; you'll pay a one-time WVB (wireless video bridge) fee to have a tech set up -- wireless uses coax network, not wifi. A new two-year re-up will extend your contract, even when adding devices (so think through your needs prior to the order).
We love our Genie and wireless mini. We also have a secondary HD DVR on network in case the Genie goes down; it's wise to do this because minis don't work if Genie is offline. We also got a SWiM-16 installed for future expansion.
Given that 4K standards are still being worked out, I believe that when we upgraded May 2014, we'll be sitting on this device for a few more years before needing to do another upgrade. Remember -- broadcasters are still at 720p/1080i, and it would require all new equipment just to get to 1080p, much less 4K. My charity work is as a volunteer, semi-pro camera director for a very large church, and our chief engineer and I have had many conversations about the state of the art. Don't sweat 4K. It's going to take a while to stabilize.
My thoughts! YMMV based on customer experience. Either way, next to the latest Apple TV (I'm looking fwd to their upcoming service), Genie is the only way to go, in my opinion.