I think another thing to keep in mind also is how geared people's teams were when they started in wotlk.

My team wasn't even 70 yet,so when I got to 70 I was wearing almost completely quest greens and a few blues I'd grabbed along the way. I went into UK at 70 and was able to get past the trash to the first boss and kept wiping there. I went back at 72 with better gear and continued to wipe on the first boss (best attempt got the boss to 50%).

I enjoyed the nexus a lot more. I was able to do all the trash, and I could get to every boss, but all the bosses except Ormorok were a problem. The mage boss (grand magus telestra) and the huge energy boss (anomolus) gave me the most problems. With the mage boss I could reliably get them to 50%, but I'd get destroyed by the 3 mages that appear every single time. I was able to finally down this boss after everyone on my team died except one warlock around 9%, I then used the soulstone on my priest to keep healing my warlock, the priest died again and I kept healing him in spirit form and he was able to down the boss.

Anomolus took a long time to figure out how to kill. If I took things too slow my priest would run out of mana, but I couldn't try to burn the boss down too quick because I had to deal with the portals he was spawning. I've only downed this boss once also.

Ormorok the tree shaper is cake. Typical tank-and-spank and move your guys around a bit if needed. I have actually lucked out a few times on this guy and not had to move any of my characters other than my tank to dodge the spikes he makes shoot out of the ground.

I made a few attempts at the last boss before giving up on her. I'd already been in the instance for 3+ hours trying to get all the other bosses and was pretty worn out.

My team is warrior, 3 warlocks and a priest.