Originally Posted by
Endus
They aren't, really. But this is a complex subject, so bear with me.
The original 5e Ranger has some issues, but it's mostly in the subclasses, and the non-combat abilities. The subclasses in the PHB aren't well balanced against each other, and the Beastmaster in particular largely fails to achieve the "class fantasy" of a guy and his loyal beast fighting together (it ends up being more either/or, not both, and the beast is almost never the better choice). Hunter is a solid pick, though, so it's more that Beastmaster fails to live up to itself.
The non-combat abilities are, unsurprisingly, in the Exploration pillar; Rangers are excellent scouts and such. The problem with them is that rather than making the Ranger awesome at them, they just straight-up obviate the need for a check. Need to navigate the wilderness? No need for Survival checks; you just can't get lost unless magic's involved. So rather than making you excel at a thing, it just eliminates the thing from consideration; it just happens. This isn't so much an issue for a video game, but it's an issue if you're the player playing a ranger at an actual table.
The other issue is that Favored Enemy and Natural Explorer both require you to pick targets; a specific type of enemy (undead, demons, etc) and terrain where they apply. If you're fighting them/in that terrain? You're awesome. Not? You lose a big chunk. This generally just "feels" bad; Ranger's fine without them, but it's irksome.
Another minor issue; there's a Ranger spell called Hunter's Mark, that lets you mark a target, and get bonus damage every time you hit them. It's critical to the class's DPR (Damage Per Round). The issue is that Hunters have limited spell slots, and Hunter's Mark requires Concentration, and lasts a long time; Concentration means you can't use another spell that requires Concentration (limits the stacking in a good way, generally), and the duration means you often use Hunter's Mark and hold Concentration on it and ignore a lot of the other neat Ranger spells that use Concentration.
Now, that all said, there was an Unearthed Arcana article that launched Class Variants that lets people swap out class features for others; it's not official content yet, but there were a bunch that let people swap out the worst of these for options that are really great. There was also a Revised Ranger UA, a while back, that never got made official. Larian's suggested they're reworking the Ranger more than other classes, in shifting it to a video game framework, so it's likely that they're making use of some of those ideas in doing so.
TLDR; Rangers are "fine", but the core Ranger has some awkward abilities that WotC has been trying to amend for some time. It isn't an overpower/underpower thing; they can do really well in combat regardless, it's mostly in the secondary stuff, and Larian's already aware of all this from what we've heard, and should be tweaking things a bit. Classes in general are fairly well balanced in 5e, but they definitely aren't trying to maintain 4e's standardization of all class effects; some classes shine more or less at various levels or in different circumstances, and that's fine.
Speaking as a dude who played a Ranger in the last big campaign he played in, for over a year (not counting the last game where I DMed, for a year and a half, or the current game which just started a month ago).