Are Mesmers still overpowered? The last time I played my team wiped on a dungeon and I ended up soloing it.
No, mesmers have been handled pretty badly in balance changes, leading to being mediocre at anything other than 1v1 duelling.
I don't pve much, but from what I've seen they are not favoured in the dungeon meta at the moment.
In pvp, thieves are a complete hard counter and mesmer has no defined role. Sure, you can easily wreck stuff in hotjoin, but that's goes for any class.
In wvw we are at a serious disadvantage in large groups - enjoy being on demand utility bot (veil, portal...).
As for roaming, lack of speed necessitates use of traveler or similar runes, and you still won't easily be able to chase down certain opponents (warriors and thieves...). Thieves again like in pvp are a complete hard counter in most cases.
Only condition mesmer builds are in any decent state at the moment - the most powerful being with prismatic understanding - but you can easily just run away from such a mesmer and they will have a hard time chasing or killing you.
The ferocity change has hit power builds hard - shatter is now a very high skill build - still my preferred playstyle, but you have to work twice as hard to compete with other classes.
Nevermind the consistent breaking of skills (now iwarden among other things), so you've got to play even better.
I could go on, but mesmer is not in a great state right now - only die hards sticking with it (I enjoy the style too much). Sure, you will still stomp noobs who don't understand the mesmer's mechanics, but against any semi-competent player or group you will have a hard time.