It's Slow as Molasses
HDMI, compared to analogue signal technology like component video (YPbPr) is extremely slow. Every connection has to be "negotiated" thanks to HDCP copy protection and the general paranoia of the movie studios who put it there.
The Cable and Connector Geometry Sucks
The makeup of a robust HDMI cable is such that it features a thick 24 gauge (or thicker) cable with a tiny little connector on the end. As a result the cable tends to pull out of the socket, or worse - break the receiving connector. Add to this the proliferation of cheap Chinese connectors floating around the world and you have a real problem.
You Can't Terminate It in the Field
Despite advances like Impact Acoustics' Digital RapidRun cable technology, for those installers using regular HDMI cables, you cannot simply cut to length and terminate the cable in the field. HDMI is too complex. The added negative to this id you lose all ability to make nice, neat, exact-length cables - having to instead settle for the nearest equivalent length you can find. Typical break points are 1m, 3m, 5m, 10m, 12m, etc... Want a 6 foot cable? Better find a manufacturer that supplies that length.
HDMI Is Expensive to Run
HDMI is terribly expensive to run when compared to simple coax or Cat5e/Cat6 cable. Just try to buy 1000 feet of HDMI. No matter how you slice it, you're going to have about a 1000% price increase over an equivalent bulk roll of coax. HDMI is overly complex and very expensive to manufacture.
They Change the Rules Whenever They Want
OK, so you figured everything out and ran the cabling for your client. You're all set - at least until HDMI Licensing, LLC decides to put out HDMI v1.4 which promises to double potential bandwidths by introducing 120Hz signal transfer. WHAT?!?! Yes, now your 3.4Gbps speed-rated cables are next to useless and you'll need to update with new cable EQ electronics (if you're lucky) to compensate for the new required supported speeds. Think this is exaggeration? Talk to the early adopters who went for HDMI back when it was v1.1 (1.65Gbps). When HDMI pulled out v1.3 and upped the ante to 3.4Gbps cables had to be replaced. Cables that were embedded into drywall. Nice.
So, what's going on now? Well, HDMI 1.3 has finally allowed integrated cable EQ to help source devices and sinks (displays) to better deal with the insertion loss generated by longer HDMI cable runs ("longer" = anything over 4 meters for the most part.) Unfortunately, this doesn't do much to alleviate all the other negatives associated with HDMI. As a result, we are now noticing a huge push in the marketplace to replace HDMI.
Anything. Anything but HDMI.
Cases in point: Everyone is coming up with ways to transmit, send or otherwise distribute HDMI... without actually using HDMI. Here are just some of the products we're seeing all over the place:
Baluns (HDMI over Cat5)
We've got companies like Atlona putting out active HDMI-to-Cat5e solutions ($329) which will run up to 130 feet of 1080p HDMI (at 1.65Gbps speeds). While that sounds expensive, the equivalent fiber solutions (another alternative to copper HDMI cables) will run you around $1000 or more. Other companies providing these types of Cat5e products include Gefen ($499), Honeywell, Intelix, Brando ($59!)
RapidRun (Active & Passive HDMI over Copper)
This one stands on its own, but Impact Acoustics has an innovative method for running and pulling HDMI throughout a home. And with their active solutions you can plug in a 5V power supply at the source and get up to 100 feet of distance.
UWB and Wireless HDMI (3.1 - 4.6 GHz)
At present, several companies are announcing Wireless HDMI transmission at varying lengths, but only a couple are actually shipping - most likely due to the complications introduced by HDMI 1.3 - which all but obsoleted many products which were in development. Wireless HDMI technology is chiefly for single "point-to-point" transmission rather than a solution for whole-home audio/video distribution at present. Gefen has a shipping unit ($699) that will do either 1080i/60 or 1080p/30 at 10 meters. Philips demoed a unit ($299) at the 2007 CES last year that seemed to work very well but has yet to actually hit the market. This one's a bit overkill, but Belkin's FlyWire system ($500+) adds video switching so that you can receive multiple sources and send them to an HDMI-enabled display (it even performs A-to-D conversion for analogue sources). Belkin is expecting to release it by the end of this year. Another player is AMIMON, however they are working with manufacturers to integrate their WHDI-based chipsets and modules into consumer electronics.
HDMI over Coax
Yeah, baby, bring it on home. HDMI over coax is the "holy grail" of HDMI signal transmission. First of all, coax is cheap and it can go for long distances without failing or degrading - especially when coupled with an active transmitter and/or receiver. Gefen currently has a unit available for preorder that will transmit 3.4GHz HDMI 1.3 over 330 feet (100m) of coax. The unit takes either 5 coax cables (without outboard active amplification) or 4 coax cables with a 5VDC power supply. The device is retailing for $499 and should revolutionize the affordability of running HDMI over longer distances. Gefen indicated to us at CES this year that they are also working on a single-coax solution as well, though they haven't yet guaranteed the level of expected performance (it may not be able to handle Deep Color like their 4/5 cable solution). Still, we're hoping everyone is working on this solution. I;d love nothing more than to see AV manufacturers everywhere dump HDMI in favor of fully-compatible active BNC coax connections.