I wasn't expecting very much from the "hubs", but think they turned out to be surprisingly fun. It's a bit like walking through the entire film- or the film's concept art- since you encounter virtually every major element somewhere in the hub. It's quite a lot of fun to drop down a giant waterfall, hear John Williams' eerie Skull theme, encounter an interdimensional being, then fly off in his ufo.
The downside is that navigating can be a chore, although this is slightly offset by the ability to pilot vehicles. Best of all, each hub has its own form of aircraft (including the aforementioned ufo) which allows you to fly over the entire area and parachute out to your destination. However, each hub is definitely designed to be a playable environment that you thoroughly explore, and doesn't lead you by the hand to the entrance of each new level. (The main menu does allow you to play any level directly, though.)
The biggest change is that you no longer have to replay the story levels 2 or 3 times in order to find all the secrets. Instead, replay is provided in the form of 60 bonus levels. These are divided into two categories: Treasure Mode and Bonus Rooms. The latter is just what it sounds like and is usually a small, unique environment that requires you to solve puzzles and collect Lego studs.
Treasure Mode is more interesting, since it provides an alternate version of each story level. For example, if you replay Doom Town, the houses have all been destroyed and the mannequins are now mutant zombies that attack you. Other times, the alternate mode will focus on a completely different aspect of the level's storyline. For example, the final level takes you straight to the alien throne room, while the alternate mode drops you into the retracting stairwell.
There are two notable additions to KOTCS's storyline. The opening cutscene begins with Stanforth sending Indy and Mac to Mexico, and ends with their subsequent capture by the Russians. There's also a new level where Indy and Mutt travel to Peru by train. The original trilogy appears in a slightly condensed form, although each film is still represented by 5 story levels (only 1 less than in the first Lego Indy).
Overall, it's a fairly large game (over 100 levels, not including the level editor) that doesn't skimp on letting you play in Lego Indy's world. You can pilot a rocket, drive a fridge(!), and tear things up in the jungle cutter. I can't really say I miss the repetitive nature of the old level design*, but I can understand why some purists might. (*SW Complete Saga stills sits unfinished on my shelf, simply because it felt like too much of a chore to unlock everything.)
But I also get the feeling that some reviewers are judging it more because they didn't like KOTCS, rather than as a Lego title. (Dear IGN, I don't recall Indy fighting Donovan's skeleton in LC, but that fact didn't detract from the SNES game.) The developers certainly don't shy away from any of the controversial elements, as the monkeys, prairie dogs, aliens, and fridge are all proudly on display. In fact, it feels just as faithfully- and lovingly- adapted as any of the previous Indy adventures. (And surely, that must stick in the craw of any reviewer who doesn't believe Indy and aliens should ever meet?
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I guess it ultimately comes down to whether you like replaying the same level, or would prefer to have something new each time. After 4 or 5 Lego titles, I was thankful for the variety. Its ambition does sometimes exceed its grasp, but I am enjoying it just as much as the Lego Indy and Batman titles.