The Nokia N8 as you know outputs 720p HD over HDMI. But the C7 lacks HDMI out, only having the standard multifunctional 3.5mm audio-visual jack. Unlike previous Symbian devices, you aren’t stuck on 640×360. You are in fact, upscaled to as close to “HD” as you can get over an analogue signal.
It’s difficult to demonstrate over pictures (I should have tried identical ones like the E7/N900 shots), but in person it was easy to see that the C7’s tv output (above) was much sharper than the N97’s (below).
Point: You’ll be getting much sharper images over TV-out. Perhaps a little bit like the N900 (or sharper) and depending on the source video, you’ll get some decent home cinema watching experience.