The mako had its ups and down. On the upside, it made the Mass Effect universe feel very large when you had to drive around on the surface of the planets and put some actual effort into finding things. The vehicle battles were also fun, I found. I loved blasting enemies into ashes, shredding them with the MG, or just charging full tilt and rolling them down under the tires. It also made for some memorable moments when my Mako was belching smoke and fire and I had to ditch it and take on a colossus on foot. In many cases, the Mako was also fun to just drive around and play with. The hammerhead, I thought, was much less fun, as you couldn't get out of it and it was extremely fragile, with just a few direct hits from a bloody pistol causing it to spew flames and alarms.
On the down side, The mako handled like a top-heavy red wagon filled with bricks. The jump-jets were fucking useless in most cases (I always wondered how they could blast the jump-jets all the way from orbit to the surface, but I only got to blast them for a few seconds) and the vehicle was prone to getting stuck in impossible places. The main cannon was also ridiculously hard to aim if you weren't sitting still, and when you did sit still combined enemy fire would rip you apart like a piece of paper. Running enemies over also had its issues when enemies would get plastered to the front of the vehicle, and made it handle like a top-heavy red wagon filled with bricks in ZERO GRAVITY.
The Mako, I think, was a good idea that they just didn't put enough time into working the kinks out of, almost as if they added the vehicle sections as an afterthought. It would have been almost trivial to improve upon it, and would have been a nice addition to the ME2 combat system. I don't see why they had to do away with the Mako in favor of cover-based linear shooting galleries, when it could have been implemented alongside this.