I have a TV just like that (just a different style cabinet) its from about 1974 or thereabouts, they were Solid State (at least mine is) and when they have proper working picture tubes they have a nice picture, fairly comparable to the Zenith CCII sets from the same time period.
But as Zeno stated they do have issues with being short lived picture tubes in these sets, mine thankfully was a low hours set that was mainly used as furniture by the previous owners who were the original owners of the set.
If its free, just go over and ask the owner if you can plug the set in and try it out (bring a VCR with a known good video tape) to test the TV with and as long as the picture isn't all washed out looking and you don't have to have the brightness and contrast cranked all the way up to see the picture and has decent color (has green greens and blue blues and flesh-tones that look normal) then the TV is probably fine, but if it looks like crap when you test it out, don't take it, that's the beauty of freebies.