Karaoke has never been my cup of tea. When people suggest a late-night trip to Lucky Voice and the idea is met with drunken cheers, my heart sinks like a limbless swimmer. Want to see my Road Runner impression? Just pull out a copy of SingStar and - meep meep! - I'll be over the horizon in seconds.

Now, thanks to Def Jam Rapstar, I can honestly say I've lost much of my antipathy towards microphones. It's surprising really, because once you strip away the bling and the online community features, this is very much a Karaoke game - albeit one where your ability to sing in key has far less importance than normal. I can't even claim to be a massive hip-hop fan; when the kids at school were discovering gangsta rap, I had my head buried in mostly-rubbish Britpop (remember Cast? Me neither - I'm doing my best to forget). I've since broadened my musical tastes, but it's equally true to say that playing this has deepened my appreciation of the genre.

Appearance-wise, Rapstar resembles a shinier, gold-tinged cousin to the usual sing-along setup. The official music video for your track appears in a window, with a bouncing ball skipping over the lyrics that appear in the space below (and above, if you're taking part in a duet or battle). So far, so familiar - but as I've noted before, Rapstar immediately makes a smart move by analysing the player's rapping in three separate areas: timing, lyrical accuracy, and where appropriate, pitch. If you test the system by simply reading the correct rhymes back into the mic, but without bothering to stay on the beat, you'll still pick up some points for your efforts. This is important, because when you eventually start to take on the harder, more complicated tracks, you'll invariably hit a tricky section where you'll stumble over the pacing.

It's impossible to fail a song, and on the lowest difficulty settings the marking is quite forgiving. However, as with most rhythm titles, Def Jam Rapstar really comes into its own once you start playing on Hard. Here you'll have to pay close attention and really make an effort to hit chains of correctly-delivered lyrics, leading to all-important score multipliers - up to a maximum of 8x. It's more of a game-like experience at this level, and it's also the best way to hone your skills. You may choke and splutter in the early days, but over time it's enormously satisfying to feel yourself getting better. By delving into the feedback menus at the end of a song you'll be able to pick through the lyrics, with the game highlighting individual words and phrases that gave you trouble.

If you're having issues with a particular section, there's also an option to practice specific verses - and in fact this is really the only way to master tracks like Scenario by a Tribe Called Quest, where the pacing switches and twirls on a regular basis. The bouncing indicator isn't much use if you're not prepped for a sudden turnabout, and needless to say it's pretty hard to get anywhere if you're attempting an unfamiliar tune for the first time. In fairness, the whole game is really geared around learning the songs: once you're confident you can removes the vocals, leaving your own voice naked in the spotlight, while the unlockable Expert setting removes both vocals and lyrics. If you can cut it at this stage and get a high score, you'll know you've got genuine skill.

Rapstar's career mode shepherds you through five tiers of tracks, requiring you to hit a specified performance target before you can ascend to the next group. It's a familiar arrangement, but aside from the fact that each tier also offers an unlockable track and a few rather useful timing challenges, Career mode feels a bit basic. It would have been great to have some equivalent to Guitar Hero's duels, or something which offered a bit of advice from the pros on the fining points of rapping - perhaps even an 8 Mile style story, of sorts; as it is, the career merely serves as an excuse to work your way through the game's catalogue.

The soundtrack features 45 tunes from over three decades of hip-hop, featuring 2Pac, Notorious B.I.G., Dr Dre, Snoop Dog, Busta Rhymes, Diddy and Kayne West, among other luminaries. Every corner of the genre seems to get some kind of representation, from UK Grime to classic '80s rap. Taste is subjective, of course, but aside from a couple of the more contemporary artists (I'm looking at you Soulja Boy Tell'em), I'd say Rapstar has a damn fine line-up. There were always going to be omissions and artists we'd like to hear more of - Eminem and Jay-Z are nowhere to be found, and I'd happily play an entire game's worth of Snoop tracks - but in general, 4mm Games deserves lots of praise for their selection.

The only criticism I can level at the music is that quite a few of the tracks have been censored. Presumably this was done for the sake of obtaining a lower rating, but I'd imagine that it could be quite a big issue for serious fans. There's nothing to stop you rapping the odd missing F-bomb, but it's hard not to lose your flow when entire lines are missing from the likes of It's All About The Benjamins. The editing isn't consistent, either: some tracks make reference to drugs and guns (albeit obliquely), while others get cut. Overall, this play-it-safe attitude doesn't quite gel with the rebellious nature of the music that Rapstar celebrates.

Elsewhere, 4mm proves that it's happier to take a riskier approach to game design. Aside from the karaoke side of the game, the developer has invested a lot of time and resources into its accompanying online community. By plugging a camera into your PS3 or 360, you're able to record videos showcasing your verbal dexterity. You can cover one of the bundled numbers or you can record your own freestyle efforts - rapping over the top of one of the excellent backing tracks, provided by the likes of DJ Khalil. Either way, the idea is that you eventually take a 30 second clip, apply some effects and stickers, and then upload it to be viewed and rated by your peers. The sticker effects - featuring stencils of dogs, cash piles and the like - are more than a little cheesy, but there's nothing to sniff at with regards to the community itself, which has mechanics in place to support rap crews, battles and all sorts of other events.

There's always been a slight question over all this, however, as it's utterly reliant upon the quick formation of a large, active userbase. At the time of writing, which is approximately one month after the US launch (the Americans got this first), things are still looking a bit quiet; there are plenty of users online, uploading their clips, but there doesn't seem to be as much rating going on as 4mm would no doubt like. Still, it's early days yet, and it's not out of the question that things could pick up with the Euro release. Even if it doesn't, we certainly can't blame the developers for trying something ambitious.

But regardless of how the community ultimately fares, there's an argument that Rapstar works best as a local experience. It's a game made for booze-fuelled parties, where pass-the-mic duets and head-to-head battles really come into their own. The latter can get fiercely competitive, with both players striving to tug the spherical score indicator down into their half of the screen - and when you're done, you can all laugh at the video of your sweaty, shouty efforts. And then you can cover the clip in silly, semi-invisible dog stencils.

At times Def Jam Rapstar almost feels closer to Guitar Hero than to SingStar and co - and perhaps, with hindsight, that's why I like it. It's a skill-based game that manages to be surprisingly technical, but never at the expense of fun. It's hugely rewarding, too: after several extended spells on the game, Mr Gaston had the balls to perform Gold Digger on stage in a Croydon nightclub - and round there, they kill people who suck at karaoke. There are certainly areas where things can be improved, and any sequel would do well to ditch the censorship, but this is a hip-hop game worthy of the label.