One thing you haven't mentioned is the atrocious CGI work, some of the absolute worst I've ever seen in a theatrical release.

Aside from that, it's pretty watchable, if forgettable. The big problem for me is they do the thing the later Die Hard movies do where the hero is an unstoppable badass who knows he's an unstoppable badass and has no fear or danger. It would be a lot better if the movie played him as vulnerable. Also, the movie doesn't seem to have a good grip on the geography and just feels kinda aimless through a lot of it. You'd think there'd be a lot of really tense sequences where he has to evade the baddies, since he's trapped in a really confined location, but it really doesn't do that. The terrorists really don't seem to put a concerted effort into finding this guy, you'd think they'd just sweep the place room by room.

The actual initial attack on the white-house sequence is quite good though.

There's a tunnel under the North Portico that goes to the Treasury Building across the street. And there is very likely now a tunnel under the West Wing that goes to the Eisenhower Executive Office Building across the other street.

There's much cooler stuff under the Capitol, including a little private subway system, since there's no place for 535 Congresspeople and their staffs to park nearby.

I thought America had more than six helicopters, but apparently not