Specialized's entry-level hardtails are split between dirt jump and XC styles. The Hardrock Sport is the former - sort of like baggy jeans to the Hardrock XC's Lycra.
The Hardrock Sport Disc's boxy main tubes lend a burly look and give enough strength. The down tube is curved where it meets the head tube to reinforce it without gussets. Even the stays are chunky, and they carry rack and mudguard eyelets. A stumpy stem gives the bike a shorter reach than you'd expect from the top tube.
The short, fairly upright riding position is beginner friendly. If you want to stretch out to distribute your weight around the bike, you'll need to consider a step up in frame size (if your bike-?t is borderline), spec a longer stem or slide the saddle right back (if it's not).
The latter gives the front end a tendency to pop up and stop you on bobbly climbs - which is a pain when the bike already ascends like a cruiserweight.
Shimano M465 cable discs are the upgrade over its £70 cheaper V-braked stable mate, the Hardrock Sport. If you want an easier upgrade path to hydraulics it's a price worth paying. If not, then it isn't. Simple. Modulation and outright bite are not noticeably better than decent V-brakes.
Those disc hubs have 36 spoke holes, however. For a bike that's probably going to be ridden down rocky or rooty drop-offs more than swoopy hardpack, that's good; a 36-spoke wheel will be stronger than a 32-spoke one. The wheels are shod with proper off-road tyres in a comfortable width for uneven trails.
Running gear is Shimano Acera. Its 8-speed Freehub is stronger than the 7-speed threaded hubs you'll often see on full-suspension bikes at this price, because the drive-side bearings are closer to the end of the axle. The bottom gear is decently low (22x32) but the big chainring may as well be a bashguard for all the use it'll get.
The Hardrock Sport Disc has a tighter focus than many hardtails. It labours on long climbs and long days, and it makes a ponderous street bike. It scores well on the ?at and downhill sections of man-made trails, or messing about in the woods. It's ruggedly built, good value, and available in a huge range of sizes. Ideal for teenagers and newbies wanting a burly, dependable play bike. Best for: Big-grin descents, play. Bad for: XC weight weenies, hurrying.