I also thought, if Walt knew he wasn't getting out of there, why wouldn't he just pack the trunk with explosives... though that m60 can fire about 10 rounds per second, the odds that every single (competent) person in the room would get hit by it have to be lower than the odds of a building leveling explosion.
Other than that (and including that, practicality be damned, the trunt turret kicks ass) I loved everything about the ending.