343 just uploaded the Mantis announce trailer:
On Wednesday I was able to get hands on with the Mantis and I can confirm that the thing is an absolute beast. It's slow but stable and packs a whopping punch, with a machine gun on the right trigger and rail gun on the left (the charge time between shots for the rail gun is about 4 seconds). At first the Mantis seems hugely overpowered, it can take a ton of damage and with a good aim can destroy any other vehicle (not unlike the Scorpion), his kill times are quick and it's quick enough that if you're careful you can usually pull back and get out of trouble.
In the first game I played I ran to grab our Mantis (blue team), but someone beat me to it, I hopped in a Ghost and sped over to red base in the hope that none of their team were aware of the Mantis. I got lucky.
Me and my team mate who had our Mantis marauded around centre hill and completely dominated the match, I got killed late on by a Plasma Pistol - Sticky Grenade combo, but the other guy on our team didn't die at all.
I know this will be setting off alarm bells for many readers.
This is why I said "at first the Mantis seems hugely overpowered", when you don't know how to deal with the Mantis it will absolutely dominate you, but 343 has clearly paid some thought to its behaviour. It has a very slow turning speed - slower than the running speed of a Spartan - so if you keep strafing and shooting it makes it very difficult for the Mantis to track you. I was able to take one down with a grenade and full AR clip (though I can't know what state it's shields were in when I began attacking it). To me this seems like a fair trade off, if you get the jump on the Mantis you'll probably kill it, if it spots you first then you're probably dead. After a few games it didn't feel as dominant as the Scorpion, but was a lot more fun to have in the playspace.
As well as the dual firing modes it also has a melee "stomp" for nearby enemies and it can teabag with the crouch button. 343 have cheekily given the mech some junk so it actually has something to teabag you with...
- Cowboy Out.