Ha, it's pretty funny that Austin was the last person to post in this thread. (Austin, I'll let you decide whether to reveal why...

)
Anyway, I just got Mazer on Friday, put it in for testing this morning, and ended up playing through the end (which took about three hours). It's so utterly a product of its time, from the rockin' music, to the hilariously cheesy character design, to the unnecessary zooming/scaling, to the buggy controls and hit detection.
And those last two things are a problem -- in so many cases I was shooting right at a boss, but because I wasn't lined up perfectly my shots didn't connect. Or I'd be turning to face a boss, and for some reason my character would stop 45 degrees away from where I wanted him to be; that got aggravating fast.
That said, the fact that I played through to the end says something about Mazer...and what it says is "this game has unlimited continues."

But actually, that's one of the game's saving graces; it allows you to figure out a strategy for each stage, and keeps the frustration factor from getting too high.
I actually found most of the game to be pretty easy -- I was able to play through the first 12 levels within 75-90 minutes at the most. The key to a lot of the game is using your shield offensively, together with turbo; that allows you to plow through groups of enemies more easily than if you try to pick them off individually.
Some boss fights were a little tricky, but I was often able to either (a) find a sweet spot where incoming attacks were few to none, or (b) figure out a way to get the boss stuck on one of the corners in the stage and blast him into smitheerens.
That said, the third-to-last boss -- Inferno II, IIRC -- is
brutal, and I spent about half my gametime on that level alone. He's fast as hell, incredibly powerful, and the stage offers no real protection (he won't go across the lava patches you open up, but that only lasts for a couple seconds). Your only hope is to get in close and unleash a combination of special attacks and melee attacks, and between that and toggling your shield, hope to keep him from triggering his buzzsaw attack. I had to stockpile an extra life or two, button-mash like hell, and have some great luck in order to finally take him out.
(BTW I didn't realize I had a special attack, i.e. what you get by pressing A+C, until this level!)
The last two bosses were much easier, though the final boss required some trickery: I got his first form caught on the scenery, and then swamped his second form with turbo + melee attacks.
All things considered, Mazer is kind of like playing Robotron as interpreted by the cast of Shadow: War of Succession. It's total cheese, right down to the "we digitized our intern" cast of characters. (The credits list four different people, but I find that hard to believe -- sure looks like it's all the same guy to me. Either way, I used Hawk for the whole thing.)
So yes, it's a bad game, but it's an entertaining and challenging bad game that never got overly frustrating despite its major, unequivocal flaws. It was fun to play through it (though to be sure it required an indulgent attitude), and likely would have been even more fun with two players. If the controls were a bit better, it could've been a trash classic; as it stands, it doesn't reach that level, but it's still worth a playthrough for those who appreciate early 1990s cheese done arcade-style.
BTW I managed to trigger at least one hilarious bug. When you're jumping in the air, if you hit a certain combination of buttons at the right time (I think Turbo is one of them), then your character will touch the ground and stay at his zoomed-in size. He was bigger than the boss -- it was as if Paul Bunyan had suddenly ventured into a video game!