Oh man I love HOTD4! I had a real blast with it in Times Square. It still retains the good 'ol zombie busting bulletfest, complete with nifty new gameplay features, like shaking the gun to reload and escape, plus the addition of grenades.
HOTD4 is much easier compared to it's predecessors, in a sense that it gives you many chances to escape injury (by shaking the gun rapidly), so this obviously prolongs play time by a huge margin. You can ease your way until the 1st boss without losing even a heath point. How cool is that?
Oh, and BTW, HOTD 4 also (unfortunately) retains the really corny dialogue all the way since HOTD2. It's kinda.......amusing, to say the least.

Uhhhhhh....yeah, apparently, you do shake the gun to reload. I don't know if there's another alternative method of reloading (the aforementioned squeeze-trigger-off-screen way), but AFAIK, shaking the gun once is the deafult method.

In my opinion, HOTD4 is far easier than any of it's previous instalments. That explains why I can finally reach the boss without losing even a health point. I find the escape feature a real godsend, since we all finally get a chance to avoid injury (during lots of tense moments when the ghoulies and the bosses grab you). In addition to that, the grenades are also extremely helpful when things get.......a little too hectic. Yes my friend, HOTD4 is lots of fun unlike the oh-so-boring HOTD3. I can't wait for the PC port.

And yeah, the dialogue........what more can I say? I'm flabbergasted. HOTD2 was the prelude for all the corny mumbo-jumbo we all endure until today (and HOTD2 also happens to have the most unconvincing voice acting among all 4 games). Sega, do something about the voice acting before I go frickin' nuts with all the unnecessary queasiness!

There's a button at the left side of the gun, near the barrel. Just press (hold on to it longer to throw further) and it'll automatically throw itself. You can even throw while shooting for maximum damage. Just remember to aim at the target, because it's not like Area-51, where one grenade will destroy all enemies on screen. It's actually possible to miss the target entirely if you're not careful.
About the reloading, remember to shake the gun only once, multiple times if you're caught by a zombie and attempting to escape. Believe me, the shake-to-reload method is more fun than it actually sounds. I find reloading much faster compared to the classic shoot-off-screen method.
And one last thing, prepare for an entire day of cramped elbows and Carpal-Tunnel syndrome.....

Good idea. Just wiggle the mouse left and right like crazy.

Well, with one credit, I managed to go all the way till the middle of Stage 2 (during my 1st try). But to spend RM20 just to reach the 2nd stage, I find that quite hard to believe. I'm serious when I say that HOTD4 is much easier compared to the previous instalments. In the past, I could only manage to reach the end of the 1st Stage, at best.