Just to make it clear. Reviews for sold titles are accepted. They're just going to be put on site with a link to the respective store.
Now the Shareware business is a little more complicated. In my opinion there are a lot of factors to be taken into account:
- Shareware types. Releasing either the full game as shareware, but limiting it in time/content - you get access through a code received from the dev, after you contact him etc. Or releasing an episode and the rest of the episodes being available in a different package which you can buy through mail/contact etc. Doom is from the second type of course. But the first shareware episode is not a full game. They clearly referred to the other episodes as the "full game". "If you want to play the full game, order the rest of the episodes." Consider it more like a demo is what I'd say.
- Biased reviewer. The reviewer already played the rest of the episodes, so when reviewing only a single episode, the shareware one, he will most likely score it based on the full game. He will never take into account that as a single episode, it obviously lacks in content. I would give the first ep. of Doom not more than 3/5 for example. Yet most will just give it 5/5.
- Commander Keen. Keen is special because not all the episodes were released at the same time. The first three were released in a batch, then 3.5, then another batch with parts 4 and 5, and lastly the 6th alone. So if you played the shareware episode of Commander Keen in 1990 and ordered "the rest" of the episodes, you'd only have Commander Keen 1,2,3. As such on many game databases you'll see the "episodes" of Commander Keen as separate games (Moby, Gamespot etc), but almost never will you see the Doom episode for example as a separate entry.
Edit: Fifth was faster than me.
