I was pretty meh about this years summer of arcade since the titles were announced. The only one that was of any interest was MNC. Today was the big day and was not disappointed. From purchase to S rank - I spent about 9 hours with the game.  Here are my impressions on what I liked, didn't like, and didn't get. 
 
What I liked   

• Balance of characters. I've never played TF2 really seriously, but I felt the characters complimented each other really well. On the contrary, each class had a unit that posed a challenge to it on the battlefield.
• The assassin. I primarily played the gunner however the assassin was easily the most fun. There's something really satisfying about cloaking yourself and sneaking up on someone and taking them out with a one hit melee.  
• Distinct maps. While there weren't a whole lot of maps to choose from, each map felt and played different.  
• Upgrade system. I had a similar fear that Jeff and Brad. I was concerned folks wouldn't upgrade their base and just buff themselves.  While I ran into a few instances of this occurring, by in large everyone grasped the concept base building. In addition, the upgrade system just felt really smart and meaningful.
• Presentation. It's may just be that I've got a soft spot for "future sport" games/movies, but I thought the presentation was well done and not too over the top. After a few matches the commentary started to remind me that of Mad World in tone, except this wasn't awful and was relevant.

•  Snipers (I just don't like snipers...in any game...)
• The tutorial. The game throws you in a pretty basic tutorial before you can play anything, but really doesn't cover the heart of the gameplay, crossfire mode. It took a few matches to really figure the ebb and flow of how games are won. There's a short video that auto plays the first time you jump into crossfire but it plays pretty quick and isn't terribly clear.
• Matchmaking. I got a little frustrated getting paired with folk with a crazy low rank. I understand everyone's got to learn somehow but would find myself with less experienced teammates and would get steamrolled against a team of better players. I found myself building turrets and activating crap while my teammates ran away from combat around the other side of the map more then once.
• Lack of maps. While they all feel different there weren't that many. I'd love to see user created maps down the line but am doubtful that will come to to be.    

• Leveling system. You earn money each match which determines your level however really unable to determine if your level actually did anything.
• Perks. I built a single custom class around how I play, however didn't notice a huge difference between that and the default.