Speed in an SP can be fun and it's something I intend on trying sometime, however, the levels you are able to speed through are often too easy, therefore meaning it's not often too fun. Well, storylines often make the game more fun (not to mention it makes it easier to follow or picture what the heck you might be shooting walls open for) and most of the best SP games have storylines alongside puzzles; take Zelda for example. The puzzles in this pack are not too hard to do and they require mere logic and I think they're really creative.
On what WhiteBlaster said, despite you pointing out the flaws (one of which I noticed too), that's still my favourite level in the whole of the lot of the packs. >O
Still, these are probably my favourite SP packs up to date, and err, what Gry said. I wanna see speeeeeeeeeed... Hm, I think UnknownRabbit made a really cool screenshot of a level that seemed pretty awesome. I barely remember it but I remember two rocks, a log, and a "JUMP" sign. Yah. Speeed. Fun. Yah. Yah. Uh. Ignore me.