In our case, the party all decided to go in the same entrance. They were fighting through the 1st wave when the 2nd decided (after a few rounds) to move around (outside) and come back in behind them, trapping them between the 1st wave and the 2nd.
It was a harsh tactic to use on my part, but it was realistic.
I used the same tactic on my players.
But they survived. It was a close thing, for some of the players (and their characters, heh), but they pulled it out without any deaths.
I ran another group through, however, and they got demolished. In that case, my observations were these:
1) Rockstars get killed. Run into the spotlight and grind your axe and you will be put down by mobs of adoring fans.
2) Teamwork is imperative. More a corollary to 1) than a separate observation, the group who stuck together, focused fire on single targets and (once surrounded) focused on cutting through one group of kobolds in order to put their back to the wall survived. The group who focused on abilities that just did the most [W]s of damage instead of granting various benefits for everyone got mauled.
3) Don't be too proud to take a second wind. Seriously, it's amazing how many players I've seen who are unwilling to stop attacking for a round in order to heal themselves.
4) Keep him moving. The group that cotton'd to the fact that Irontooth only got to use his double attack if he didn't move managed to avoid a lot of the trouble that the other group choked on.
5) Action Points are king. The TPK group used their APs for Alpha Strikes, front-loading their damage against the first wave -- and while they inflicted a lot of damage, they didn't have the adaptability of the other group, who conserved their AP and used them at strategically appropriate times (Wizard who thunderwaved the kobolds off the cleric followed by a burning hands to target the now-perfectly arranged little suckers for oodles of damage; fighter who attacked and followed up with a second wind so he'd survive the inevitable counterattack).
6) Avenging Fire (Cleric Daily) is Nasty. You have to sacrifice your attacks in order to make a saving throw, and even then there's a chance you'll fail your save. This power was the real Irontooth killer for that group.
Edit: Perhaps unrelated, but somewhat interesting nonetheless --
The group who worked together and overcame the challenge (they actually did both the outside encounter and inside encounter(s) at the same time, in fact) were players who were coming over from 1E and 2E.
The group who focused on individual power and personal spotlight (and insisted on a full rest after every encounter, and who got massacred) were all converts from a 3.5 game.
Take from that what you will. (Youth vs. Maturity? System tropes? I dunno.)
