This product is basically a wireless extension for Composite video, i.e. the single-pin yellow connector on all TVs. Even the best signal when sent over Composite is no match for the quality of the RGB-SCART or S-Video connection that most people will use to connect their digibox/DVD player to their TV. So this product will never be good for any screens above about 15".
Considering the above quality limitation, the wireless signal is reasonably robust, but being an analog signal it suffers from unpredictable interference. So one night it might be fine, then the wind changes and you need to re-adjust. I find this on my setup and I'm sending the signal about 10 meters through two wooden internal walls. It's likely the neighbourhood's dense Wi-Fi is causing some of the problems. Switching our Microwave on completely zaps the signal, though this is to be expected.
So overall I'm pleased enough to use it for our small bedroom TV, but I wouldn't recommend this product to anyone who dislikes the quality of Composite signals because the actual quality is worse than that.