Cliffhanger is pure winter fun - I raised the grade from C+ to B-.
Sherlock Holmes makes good use of the "drowsy" icon.
Only flaw I've noticed, except after reading the review twice, I've no idea why you didn't give Sherlock Holmes an F. I enjoyed cerebral games, but in the very first play, this game went out of it's way to bore me. The fact that you're rating it higher than Maniac Manion for the NES, which only suffers from a slow cursor and asking the player to think outside of the box, suggests that either you have a grudge against Maniac Mansion or were intimidated by Sherlock Holmes...
I tried playing Sherlock Holmes and it really does require an unbelievable amount of patience. I do think that D- is accurate, though, because it is a very good showcase for the FMV capabilities (as limited as they are) of the Sega CD, given how the video is clear and the acting is pretty good, two things that FMV on this system often isn't.
As far as being an effective pack-in game with the Model 1 Sega CD, it was came with a ton of stuff to show the system's capabilities off anyway, so this coming with it, I think, represents Sega wanting to cover all their bases more than anything else. It can play CDs, so here's a music CD. It can handle CDs with graphics programmed with the tracks (kind of like karaoke), so here's a CD+G disc. Oh and here are a bunch of games; Sol-Feace (an enhanced version of Sol-Deace on Genesis) a Genesis 4-Pack (Golden Axe, Streets Of Rage, Revenge Of Shinobi and Columns) and, to show the FMV off, Sherlock Holmes.
If I have several versions of the game, it's easier to review them all at the same time, because they are easy to compare against each other.
Don't worry you're safe - until my NES review!