Some perspective required I feel - theres a lot of 'OMG!!!' 5 star reviews knocking about, and yes this is a fantastic attempt to bring Motorstorm to the PSP and theres a lot thats great about it, but ultimately its only an average game. I love it for trying, but theres too many niggles to make it stand out.
I think ultimately you have to consider what made Motorstorm and Pacific Rift great on the PS3 and what made them bad - on the plus side, they were both technically adept, and visually stunning, there was a lot of pleasure to be gained just from watching the track deform or the cars get dirty. A large element of the PS3 versions was battling the track itself, picking the best route through the landscape and each surface required a subtly different approach leading to a 'no race the same' feeling.
So straight away, theres one issue with Arctic Edge - graphically it ranges from nice enough to utterly hideous. Car models are basic and chunky, damage is poorly done, trackside objects obtrusive and dull. Some of the more open ended snowy tracks are nicely done with a good sense of scale and some lovely landscapes and lighting. The snowy tracks deform well enough (albeit in a chunky fashion) and the track design is usually fairly compelling - however other tracks are an exercise in hideous colouring, texturing and bad layout. Being crammed onto the naturally underpowered and small screen PSP you lose a lot of the technical fidelity that helped drive the experience in the PS3 versions. Aside from the obvious snow, track surfaces are difficult to differentiate between, meaning there is no tactical awareness of the terrain - you always follow the shortest route regardless of what the surface is supposed to be. If you're like me, you end up following whichever route is more visually pleasing.
So without the detail and information from the track to help the experience, you have to rely on the other racers to provide the spills and thrills - and unfortunately the old Motorstorm problem rears its head here too. The earlier races are far, far too easy. You'll be clear of the pack after the first couple of corners and then open up an unassailable lead with no problems, finishing literally a minute or so ahead of 2nd place. Theres no jostle and battle with the pack here, usually such a core part of the motorstorm experience. And then as with all Motorstorm games, the difficulty spikes suddenly making races far too hard - unboosting AI racers can travel as fast as you when you're boosting, a criticism you can level at all the Motorstorm games and a shame that its one thats made the transition to PSP.
So with the main hook of the Motorstorm series stripped away somewhat, you're left with a fairly solid, but average racer - not the developers fault I would say, more the technical limitiations of the PSP which means the console isn't naturally condusive to recreating the whole Motorstorm experience. So an entertaining enough racer, with the odd nice touch, but thats not what you buy Motorstorm games for - you buy them for the spectacle of the landscape, the carnage, the mud and dirt, the tactical track decisions, the rough and tumble of pack racing on the edge of a cliff - all features that are sadly lacking or toned down here by necessity.