Hello guys. Let me try and help since I played WHRPG for 30 years or so. My knowledge of the rules and system doens't include the last edition(s?) but I think the spirit should be the same. First it's a "low fantasy" RPG. This is a major point. It implies there's not magic items to be found everywhere so the characters won't find themselves with magic rings on each fingers and 5-6 magic weapons to choose from depending on the foe facing them. I personnaly prefer that, because magic remains something very special and mysterious, not just another tool. Also, about magic, it's not as powerful as it could be in other RPGs, because its essence is chaotic. You may try and tame it, but a failed cast implying a very very bad roll can have consequences for the sorcerer (he can start bleeding, glowing or worse...) or even his entourage... Second I'm just fond of the way characters evolve when they gain experience: They have carreers to pick from, they can gain different skills, talents or characteristic bonuses depending on the carreers path they choose. It may lead to optimizing characters but it can also be a lot of fun to play unusual adventurers (I had a lot of fun not too long ago playing a cheerful master cook). Regarding this matter it'll depend on the gaming group, not the game. Third, it's a lethal world. Each fight is very dangerous so you have to ponder options and plan, you can't just rush headlong. Also, there's a real feel of achievement even when you survive encountering wolf-riding goblins. It's also a dark world, with chaotic cultists everywhere (well, almost everywhere) and frightening things lurking in the shadows. Last but not least, WHRPG definitely provides among the best campaigns to be ever played. And even the old ones can easily be adapted to the more recent game systems. For all these reasons this rpg is my favorite one along Call of Cthulhu. Now, is it suitable for beginners, well I don't see why not if they're open to rpg and can take a little frustration in the beginning (I mean, if they're used to play super tough characters such as the ones you find in video games, the first fights will be lethal for the players. They have to be cautious). Gotta run. Please ask if you have questions, it'll be a pleasure to help.
Yes, those a very different games, especially since D&D is more "high fantasy": there's a lot more magic stuff going on everywhere. You can even shop for magic items depending on the scenario you play, which isn't the case in WH, where magic items usually appear to be like long time lost relics. Another major difference between WH and D&D is that, imho, the world of WH is very detailed when D&D depends on the "setting" you pick, and even then, the geography and the political/religious/racial dynamics can remain blurry. Oh and since I'm discussing WH/D&D worlds differences, D&D feels like playing in the High Middle Ages (a common rpg feature) when WH feels more like Renaissance, which adds to its uniqueness.
I can't say too much as I havn't yet played a game, but reading through the rulebook it does seem fairly straight foward. A friend and I tried making a test character and it only took us about 15-20 mins and we had a playable human outlaw, for our first time opening the book that was pretty good, I remember taking 40 odd minutes making my first D&D character. The character has a great way to quickly make a random character with a few dice rolls, and it leaves you with a lot of experience points to buy more skills or stats, so thats a plus in my book. The actual rules seem pretty straight forward as well once we found the right passage in the book (to be fair we were skipping around a bit). All skills and tests use the d10 or d100 so no getting your dice mixed up. All in all I would say it's pretty easy to learn the basics and if you have an hour or 2 to go over the rulebook you could probably be well on your way to getting the advanced stuff down too.