One of the X-Men's Most Memorable Battles
This issue is pretty much an all-out battle between The X-Men and The Juggernaut inside the X-Men's mansion. There are a handful of minor quibbles here, including editorial mistakes like Marvel Girl referring to her telekinesis as 'teleportation' (again), and an annoying (but thankfully brief) cameo by the 'Teen Brigade', oh, and a Danger Room door made out of wood... but overall, this issue is about action - a non-stop battle - and as such, it's better than most issues.
The Juggernaut is loose in the mansion. The X-Men fight a delaying action while Professor X supercharges his own powers. The professor also manages to contact the Human Torch to supplement the team.
Ultimately, like most early issues of The X-Men, Marvel Girl is under-utilized, and Angel is over-utilized; it's especially apparent in this battle where the final defeat of the Juggernaut is largely thanks to The Beast and Angel when Marvel Girl could have accomplished the same feat much easier via telekinesis.
Still, the X-Men's first fight with Juggernaut is probably one of the most memorable battles in their history.