While fragility of individual soldiers is absolutely key to X-Com's appeal (the knowledge that if you don't move slowly and methodically a character will end up being shot, leading to the being unavailable in later missions, etc) one of the different design choices leads to it being too much. And it's one which, on the surface, would make it appear to make the game easier.
Soldiers can't die.
As long as you win the battle, your soldiers will be brought back to the base and recuperate (there's an ingame justification based around some high-tech), ready for the fray. The problem is that, unlike X-com, you can't purchase new soldiers. New troops arrive at a steady rate, and you're left twidling your thumbs if everyone's in the sick-bay (you can purchase tanks, but they're unsuitable for taking on missions by yourself). This was presumably to leave more room for the RPG-esque advancement of characters, but - in practice - leads to frustration and game-restarting (expect at least one cold restart when you realise how badly you've screwed up). Since you can lose soldiers permanently if you lose a mission, it tends to mean that when a mission goes seriously wrong, you have to restart or else risk rendering the whole campaign unplayable. This is a major minus.
There are some odd interface choices too. The control system is generally an improvement over the 94-model, but some actions - like kneeling - are tricky to access. Stranger still is what's missing - specifically, a map function to give you an over-view of the mission, which is particularly confusing on the larger maps where you're trying to make sense of the conflict.
To give it credit, some of the best features of X-com are present, such as the ability to destroy most terrain objects. There are few things as heroic as a soldier blowing their way through a wall to take out an alien about to finish off his team-mate, but other strategic worries are absent. For example, you're able to access the inventory without any action point penalty. You can swap weapons and reload as much as you like, which makes things considerably easier on you at the cost of imagining your soldier casually weighing up the pros and cons of the shotguns and rifle before actually taking the shot. And that's about all you'll be weighing up - especially in the early days as there's a real lack of equipment variety.
Graphically it's functional at best, and laughable at worst. Particular nadirs are the intro sequence - one of the ones which designers would have been smarter dropping as it makes such a bad first impression. Also a bit rough are the civilian humans in the Terror missions - where aliens attack an actual population centre - who move at such a lackadaisical stroll to imply total calm. I haven't seen anyone as laid back in a videogame since early-nineties platformer Cool Spot. It's like the aliens have decided to attack the Fonz's house or something.
Then there's the issue of plagiarism, on which I'm actually conflicted, despite everything I've said earlier. You rip off a concept which eight-thousands people have ripped off, you're just working in a tradition. You rip off something no-one else has been brave enough to, you're a plagiarist. That doesn't seem fair - surely it's better that we have something akin to X-com to play in the modern day? Imagine if there hadn't been a one-on-one fighting game released for eight years or so. That's a bit like this.
But in this case, I think what actually annoys is the exactness of the lifts - for example, the Terror missions - which grate. If this was an X-Com-clone with some obvious ideas of its own, it would be easier to forgive. When it really doesn't, you end up recalling that the Gollops are off working as an independent-developer on great-but-minor games like Laser Squad Nemesis and the Game Boy Advance title Rebelstar: Tactical Command. In any fair world they'd be - oh, I don't know - Britain's answer to Sid Meier or something.
That's very much a secondary issue. There are enough flaws in it to stop recommending it to anyone but real X-com fans - who, it seems, are busy trying to mod it into something closer to their desires. If you're not one yet, but are intrigued by the vague prospect, it's worth noting that the X-Com sequel is up on Steam at a very reasonable price as long as you don't have Vista (no, it's not compatible). Everyone else should probably sit back and wait to see what 2K Games is actually going to do with the X-Com license...