I can only really speak for PvP, since I haven't done any real endgame PvE on my magden.

Right now the class is overall extremely strong in PvP. While they are lacking a bit in solo Cyrodiil and 1v1s (unless you have a dedicated duelling build maybe), they really start to shine when you have at least one ally who complements the class well. Yesterday, I had some good 2vX moments playing my magden together with a stamden.

Furthermore, they are arguably one of the best classes for BGs, hands down. As far as I know some PvP raid/ball groups also like to bring one magden with them.

From my experience the class works well as:
- AOE pressure dd build (what I'm currently playing)
- Tanky support (usually spamming immobilizations and such with wall of ice + class skills)
- Dedicated healer (altough for some reason rather rarely seen)

I play Magden in PvP also, everything @HankTwo said is pretty spot on.

Damage
-Single Target: the class stam/mag max parse gaps have narrowed considerably; within ranged mag it's very narrow
-AOE/Cleave (stronger): still really strong while several other builds have lost power in this area
-Execute (still bottom barrel): no execute skill other than bear cast BUT none of the bear damage is modified by bloodthirsty whatsoever still; making it is worse than even MagDK's execute

New Toys
Minor Vulnerability
useful in dungeon/arena and for trial adds, PvP
not really trial bosses as Warden healer or tank is almost always present but would give them a skillslot or serve to enhance uptime in progressions/farms
PvP useful always

Off Balance
potentially a little benefit in mixed dungeon challenge and PvP groups.
Minimum range prevents potential utility in trial stacks

PvP Stun: haven't tested enough or heard much to convey effectiveness but there apparently is a stun skill in our kit now

Now Exclusive Toy
Minor Beserk only class with it left as NB lost there's; nice to have in trial portals, dungeons, arenas

No longer exclusive Toy
AOE Major breach as Magcro, Tankcro, and Healcro have it

Other
-Other warden buffs really are best applied by Warden supports although it's not the worst thing in the world to slot the new altar to give toughness if say a Warden support dropped out of the run eg
-Same range situational downside: Magden still has non-max range skill in rotation unlike Sorc, Temp, and Necro
-Master Architect still useful now that mag groups are used once again; Temp/NB can as well; Warden has a little leg up being able to proc from range
-Still limited to using bear, although I've reviewed logs in which for trash you can do about equal or sometimes better with Mage's Guild FB / North Storm BB

For me it's gone like this:

Friend: "Can you sub DPS now?"
Me: "Sure, on magden, ready for invite"

Wrathstone: "lmao, whisper me after you swap"
Elsewear: "got a stam?"
Scalecaller: "hm, maybe that could work...I'll ask RL…can you hit XXk with that?"
Early Dragonhold: "eh, that'll work" invite sent
Now: invite sent