I used to love rogues for their flexibility. In 5e I don't.
1. They're too DEX-focused. Most classes can produce competent builds without at least a 14 in the presumptive main stat. In my experience, Barbarians and Rogues are the classes that fail this test -- there should be diversity in builds, but there aren't. Charisma Rouges, Intelligence Rogues, Strength Rogues should exist much more than they do. (I've just started playing a Wisdom Rogue, but even still, a Dex 14 seems "needed").
2. They don't have a niche. As described above, Rogues are often though of as skill-monkeys or the high-damage striker. Neither of these holds true: Bards quickly outclass rogues as skill monkeys (and are supplemented by a full swathe of utility and healing spells); and the viability of sneak-attack damage is not obvious.
(I've seen many fighter-archers; few rogue-archers. A well-designed class should present a real choice for archer builds, with two different but equally viable possibilities. I feel that isn't there.)
3. Mundanity. I feel the hurt particularly since so few options for non-spellcasting classes exist. Fighter I feel is robust and diverse. I wish I felt the same for the Rogue.
One thing rogues do do, that I wish was exploited more is this:
4. Intersection with Backgrounds. I find this particularly robust, with the possibility of Acolyte Rogues, Sage Rogues, Craftsmen Rogues, Soldier Rogues. Each of these should be amazing. But I don't see the possibility of cool combinations being made often enough.
(Back during the 5e playtest, in the beforetimes, when they first introduced backgrounds, I wanted Rogues to have two backgrounds (and get their extra skills that way). I still think that would have been awesome -- rogues by their nature would be noble/thugs, or acolyte/soldiers, or charlatan/craftsmen, or whatever.)