It's too bad that this game kicks off with its infamous "WHEAR'S THAT WARRANT" line, as it's actually a perfectly acceptable brawler with an undeserved bad reputation. Yes, it's a shameless Final Fight clone, and no, it isn't as gritty as FF, nor does it feature characters and tunes as memorable as FF's. But it does boast smooth controls, nice backgrounds, and huge sprites (which, admittedly, are not animated very well).
People cite the relative lack of "moves" as a major issue, but I don't particularly care about it, as I'm a button-masher for the most part when I play old-school beat 'em ups, and I find that hard-core fans of the genre who make claims of utilizing "strategy" are usually full of crap. It's rather odd that the designers didn't include canisters and the like to annihilate and weapons to pick up, but again, such elements typically play minor roles in brawlers: tossing the occasional knife or lugging around the occasional wrench never adds much in the way of "variety" for me.
Lack of a two-player mode is something that even I find fault with, however. (The omission comes off as especially egregious when the two heroes pledge to "go down fighting together" in the heartwarming opening cinema.) Also, the adventure drags a bit towards its conclusion. The developers did a decent job as far as early-stage enemy variation goes, but the the same few bums appear ad nauseam during later rounds. This is typical for a brawler, but even the tunes repeat themselves here.
It all leads up to a final battle that the designers had a nice idea for (but consider yourself warned that the last boss, as well as all of his cohorts, is easy as cake to beat) and that's accompanied by a quality tune, one that starts off with Metallica-esque riffs before hitting its stride with a catchy hook. Most of the tunes are pretty good, actually, although many of them are a little too laid back and upbeat if you ask me; I prefer Final Fight's urgent, gritty numbers. I must admit that I get pretty pumped up whenever I hear the track that plays during the opening cinema, however.
There's no way that Riot Zone deserves to be lumped in with the likes of Rival Turf and Captain America at the bottom of the old-school-brawler heap. Sure, it's a "biding time" sort of affair, and it isn't likely to engross you, but if you're willing to accept that, you'll probably have a good time with it.
The designers came up with some cool enemy and environment designs, but repetition does become a problem during the last few levels.