They're pretty perfect except for Spire (Banshee camping Elite spawns) what you don't like about them?
Everything about them sucks.
Boneyard works somewhat okay with 12 players but Breakpoint is definetly done with 16 players in mind. The Spire works ok with 12 people but it starts sucking really bad if either team loses even one person.
All of the maps are too large, they lack easy way to get to front lines if you chose a wrong spawn (accidentally, forced, thought you would get something but didn't). The Spire especially suffers from this.
Boneyard's extraction zone and the route to it is horrible. Boneyard's Spartan vehicle spawns are horrible, the Elites can just wait till the tank comes slightly out of the garage and blow it up. Besides, the Scorpion has no place in Halo multiplayer, it is just that overpowered, no amount of tweaking can change that. (So is Reach Banshee...)
The Spire's final phase is idiotic too, people just throw down the core and then it is a race to whoever gets first a bubble shield over the core. That is, if the Banshee is not a factor. The second phase is stupid due to Armor lock and, IMO, bad placements of the "hills", two small rooms with just one entrance...
Both original Invasion maps have okay first phase though precision weapons can make Boneyard 1st phase really awful, too little cover for the Elites from high ground.
Breakpoint is just bad. The extraction is even worse than the others, just a long direct line without cover. The core being a "support weapon" was a stupid decision as it makes use of vehicles impossible in practice.
All maps suffer from this idiotic "defenders can go to camp attacker spawns". Defenders should be defending, the map desing should not allow them to be "attackers".
EDIT as i said, Invasion can be fun with a full party (preffably having the other team also people you know won't quit, ie HaloGAFers) or when people don't quit but play seriously. But those matches are rare. And the maps themselves certainly don't make the game fun.
