I have the EyeTV Hybrid to digitize old 8mm tapes. It works well enough, but I wish there was an option to record at a higher bit rate, or even better, use a different software encoder. Elgato tells you that since encoding is done in software, the quality depends on the speed of your machine. That's true to a point, but it caps at roughly 6-8Mbits. In theory that should be more than enough, except the encoder isn't too smart, and you'll commonly see pretty horrible pixellation at times - especially with regions of similar contrast, such as water or snow. There's definitely more processing overhead available for the encoder - my MBP utilizes only about 20% of both cores - so it seems to me that the situation can be improved with better software.
Anyway, it's good for grandma and grandpa, but nothing more serious than that. I'd do like others have suggested and get a DV camera with an analog passthrough.