I spent an hour playing the career mode. In terms of the mechbay and management screens, I prefer the HBS version, but otoh the HBS game is slow as shit even on the menu screens. MW5 is fast and smooth at everything, loading takes seconds, it's a great experience in terms of performance. I just don't know why the mech market is accessed from a different area than the regular market, etc.
In terms of combat... I would describe it as MW4 Twitch Edition, or maybe MW4 Lite. My mech turns on a dime and moves very fast, although that might be because I was piloting a Javelin. It did not feel like MW: Online, but maybe the heavier mechs handle a lot differently. I wouldn't say I hate the handling, I just prefer my memories of older MW titles. The pace of combat in this version makes it feel less cerebral, and some of the mech control options are inferior or outright missing. For example, the option to look to the sides and use your arms, which was well done in MW4 and I used it frequently - you would hold down a key and it entirely shifted the view, while the mouse would do the fine aiming at that new perspective.
The lance instructions are simplified to the point of being useless. It doesn't seem to matter what I tell them, they kind of do their own thing. Maps don't have extensive nav-points like MW4, and even if they did there is no option to tell your lance mates to go to a nav point. At most you can aim your weapons at a spot you can see, and tell your lancemate to stand there. Whether they obey or not is up in the air. Speaking of nav points and lite-edition, that brings me to the fact that hand-crafted missions are superior to randomly generated dogshit.
The missions I played just involved a generic paragraph or two describing the mission objective, and then I was just dropped in to what is closer to a multiplayer death match game. The enemy comes in waves and you do your best to kill them, and then you win. In an older/superior game like MW4, the missions had a detailed explanation, and that explanation tied into a clear mission structure that you played through as you went from nav point to nav point. There were some nice plot twists too, like the enemy surprising you with a trap and the nav points/mission changing on the fly, and your teammates were easy to order around and they worked well with you.
An hour is not enough time, and I have only played a light mech, but I get the sense that this is a slightly shittier version of mechwarrior 4. I did enjoy playing, and I would increase the score to MW4 or better if the mission structure improves and I have some opportunity to explore the maps and deploy particular tactics. There are apparently flashpoints, which are hand crafted missions. There's also a campaign, but I don't think I get to play that until I reach level 4 in career mode; maybe the campaign is amazing and will change my thinking.