The Nexus is a lvl 71-73 Instance. The whole area outside and inside is visually stunning in design.
Instance is a bit long. Longer than Utgarde Keep with lots of hallways to navigate. You can just about get lost navigating some the halls. But their are different wings in the instance and it changes to reflect the area or wing of the instance. Lots of various mobs here mix of casters, physical, plants, rifts and some Shade looking mobs like in Kara you like to hate.
All the Bosses here are interesting and fun and of which they are 4 and will leave it at that. A group in Green/Blues will find the Instance challenging I would think. A few the fights were challenging for our group with most wearing mostly Epics with exception to the 70 Death Knight we had. We had a group of: 70 Warlock, 70 Rogue, 70 Death Knight, 77 Holy Paladin (T5) and myself as Tank. Only person being here before was the Holy Paladin.
This Instance have quite a mix of mobs and a bit of casters. We didn't wipe on any the bosses but almost did one with thanks to Devine Shield for a wipe save to get healed. Its a really fun instance and really nice looking. One the most annoying part of this instance is a few of the mobs that currently will stun the tank silience "back to back to back" which seem like eternity being spell locked silienced on some hounds.
It was damn annoying first time causing aggro loss but managed it and recovered, 2nd time it happened again and caused a wipe with a already pulled group. Others have reported being annoyed by this mechanic as well. Hopefully the devs fix that as its not fun at all.
Had aggo problems at times but was always to the Warlock. Again no threat meter and no Salavation either. Used Hand of Salvation once on the Warlock since had Taunt on cooldown, but felt real ackward using it when had to. Time will tell how threat plays out with aggro.
With as much server crashes Northrend server has being having was amazing we didn't crash in the instance when we were there. Overall a fun Instance and shaping up to look really nice all things otherwise.