Having played the beta version of 5e for over a year now, there's a few things I've noticed as a DM:
Fighters are useful. They have a decent amount of skills that translate well to non-combat scenarios, surprisingly. Certain enemies become both easier and deeper in combat against a fighter, as well. Death Knights, for instance, have a particularly interesting flow to combat that I'd never seen before this version. Previously, I'd only really seen them be a fairly normal, if tough, enemy that hits hard with magic and melee, but in the 5e beta, they also had a number of reactions and some fun effects that helped make fights more dynamic. Granted, I should probably mention that I got into D&D during 4e and thus you can assume all that entails.
Rogues are not nearly as vital to a fully functional party if you have creative players. I've run into situations where a low-leveled ranger and cleric party were able to get through a relatively hard dungeon without dying. A particular example from another game had a combat mage freezing and heating metal bars so that the Barbarian could rage her way through with a maul. Granted, some DMs might not account for special effects on obstacles, but the rules kept everything generic enough that attacking a wall could be a viable tactic in certain situations. I feel like criticizing the system for leaving certain things to the DMs discretion is unfair to the way tabletop RPGs work.
The other classes, Druid, Ranger, Barbarian, etc. have all come across as fun and diverse. They each play very differently and even players entirely new to D&D seemed to understand their roles pretty quickly. To be entirely fair, the Ranger class is more like a combat-centric rogue while the Druid is the same for mages. They do offer a different experience from what I've seen, though.