(Quick note before I start: I have not been able to playtest the new material although I will soon. This is just my opinion on reports from playtests I've read here)

There has been a lot of complaints here about the rogues lack of identity. Their grounds as the "skill monkey" has been lost to the other experts, and the flash damage from Sneak Attack isn't enough to carry them. However, rogues are so much more flexible than the other experts. Bards are going to be better at persuasion checks, rangers are going to be better at survival checks, and artificers (if they get the expertise like other experts) will be better at arcana checks.

However, Bards aren't able to do survival checks as well, Rangers can't make great faces, and Artificers can't do much out of int and tool checks. Rogues can do all three depending on how you build them. A rogue can have high CHA and get expertise in persuasion and deception, rogues can get a high WIS and get survival skills, and a rogue can go high int and be the brains of the party. And, because rogues only need 1 good stat (DEX) they can probably get fairly highs numbers in two different stats and fulfill two roles at once. Bard and Rangers are less able to do this, because they need their casting stat, con for concentration checks, and dex.

Of course, Rogues still need a bit of tweaking to fulfill the role of "dirty plays and tricks in combat) which they can't really do. Along with this, a rogue needs a party with 1-2 holes in terms of roles in order to shine, and a more complete party is difficult for a rogue to feel important in. However, their flexibility means that they can fulfill more roles than bards or rangers can.