I don't think that was it, exactly. From the sounds of it, and everyone agrees, there's no challenge. Straight away that has to take serious points from the title because that's more often than not the very basis of any gameplay - here's a challenge and your skills overcome it. So if you then couple lack of challenge with loads of different things, it's not a huge a leap to say Insomniac lacked focus in making a killer game. Though I don't agree with everything said, that review vid does provide a POV that I can at least see as generally fair. If the game has no challenge, I'd probably score it on the low side of good too.
There's enough challenge, though admittedly there's not a huge amount. As with platformer heritage, there's usually not "challenge" so much as "repeating things until you get it right." (The main game of a platformer, due to the audience it's aimed at, is supposed to provide some challenge, but with repetition able to get you through most times, and the REAL challenge being those additional extras you can pursue afterward. The "main game," however, needs to be fun over "challenging," and for any mature gamers is usually along the easy side.) R&C's own heritage draws in some added "challenge by finding just the right weapons to use, or trying to perfect your spanner use so that you conserve ammo and get more bolts."
For everyone else, though, there's "having fun blowing shit up."
Reading their review, though, it seems like their biggest complaint is with the story, even though they say "it doesn't matter much." (They seem to mention it the most, though.) And, of course, for games like this you normally don't have ANY story, or you basically have crap story, so... It's almost like they count R&C's attempt TO include story against them, because even though they're mainly having some cheesy fun with it, if you start putting ANY kind of serious thought in, you need to immediately be like a full-fledged RPG.
...and all things considered, if you can get through the first 7-8 planets with only one of those "identity crisis" extras (one extended rails scene, one Sixaxis-controlled falling scene [what you see in the demo], one flying scene, one rails spaceship shooting scene...), there's really not all that much to be confused with. Unless the spacing of them goes straight to hell in the second half of the game, I don't think there's much to latch on to. It's just one of those "somethings extra" that they toss in to add variety, instead of doing everything the same way. It doesn't really matter if you're using springy goop to bridge a "not normally jumpable" ledge or gap, or you're using rocket boots, using a laser whip, robo wings, a jumping pad, a teleporter... They're not difficult elements, they're just fun in slightly different ways, look different, and let you experience the board in different ways.
R&C is really just as glorious as ever, and "more random fun" is never a bad thing.