Is HDMI 1.3 compatible with with my HDTV and is it worth it?

There is no such thing as a HDMI 1.2 or 1.3 cable , thats not how it works , the cables are the same regardless , the 1.2 and 1.3 specification is what your devices ( TV , DVD , AMP etc. ) interface is capable of , HDMI 1.3 adds Hd uncompressed audio and Deep color to the interface , but it travels down the same cable regardless , the spec applies only to the devices , not the cable. The issues that you might come up against here are not related to the cable but more to the devices connected with them , for instance , theres no point in having a HDMI 1.3 source if your sound system or tv cannot handle 1.3 content. This being the case you will default back to 1.2 specs.

http://en.wikipedia.org/wiki/HDMI

The only way you would need to change the cable is if you wanted a longer run , if , like most people , you are using a cable less than 10 meters long then that cable can handle anything that your devices can throw at it regardless of what spec interface your sources have.

There is unfortunately , a lot of price gouging going on with HDMI cables , some rated at 1080p , some rated at 1080i , if they are now rating them at 1.2 v 1.3 then this is just another form of dishonesty regarding cables and should be ignored , any HDMI cable less than 5 meters for instance , can handle at least 3 x the bandwidth of the most intensive signal thrown at it , which at this moment in time would be 1080p deep color content with a HD audio soundtrack. ( and note that such content is extremely rare ...currently the only HD audio sources are DVD audio , SACD , and neither of those comes with much video content. Most Blu-ray comes with a standard Dolby 5.1 soundtrack and not HD audio).