It took a little while to get used to the drums. The two-tier structure with the cymbals feels great, but can be slightly confusing at first. The drums are a lot bouncier than the Rock Band ones, making them not only quieter, but more fun to play. With Rock Band, the bounce seems to come more from the way the sticks are held, rather than out of the structural nature of the pads. Not hearing the constant thok, thok is definitely preferable too, as anyone who has bought silencing pads for their Rock Band drums will know. [Editor's note: Rock Band 2 also features quieter, bouncier drums.]
Having five drums, rather than four, also takes some getting used to. It wasn't until midway through the first song that a blue (middle of the lower tier) note appeared, but it spun me for a loop. The one issue I faced continuously was my sticks getting stuck underneath the cymbals at times, but this is no doubt fixable by adjusting the heights of the pads. World Tour's drum set is definitely preferable to Rock Band's overall, though this is only in comparison to the original set, not the forthcoming model -- and certainly not the premium ION set.
As for the guitar, if you have Guitar Hero III, then you already know how the instrument plays. It's the same design and feels almost identical. The new guitar has a few extra features, like the touch panel strip. Hammer-on fans will love this. On certain note sequences you can slide your finger along the strip, making it feel more like sliding up and down a guitar string. A pretty decent idea, but in practice it suffers from the same problems that the Rock Band's guitar does with its solo buttons. Moving your hand into position at such short notice is guaranteed to put you off.
Another new addition is the star power button, which is long and thin and is activated with your palm, in case you're feeling to lazy to tilt your controller. A pretty pointless addition, unless you're using it to palm-mute notes in the song creator. The World Tour guitar's whammy bar has also been improved, making it far more resistant. I may be in the minority here, but I still prefer the Rock Band guitar. Between the buttons being flush with the fretboard, the feel of the strum bar and the overall design, it's still my number one choice.
I didn't get to play around with the create-a-track mode but, from what I saw at the press conference and heard from Brian Bright, this was probably for the best. The idea is sound, but the implementation looks horrifically complicated and technical. As someone who's experience with creating music is very limited (read: none), the thought of using the create-a-track mode is almost tortuous.
Again, it sounds like an interesting idea, letting you change the pitch by tilting the guitar or customizing your chord list; even using your guitar to lay down a keyboard track or a drum beat, using the built in drum machine. From what we could tell, however, you're only going to be able to create something good if you have real world knowledge of writing and performing music. In which case, why not just do it in real life?
In the end, the create-a-track mode seems perfect for indie bands who are looking to get their music into the game. As for the casual family audience, or even the non-musical hardcore audience, this is one bullet point on the back of the box that is going to be played with once or twice, then completely ignored.