I've always found them to be reliable. I've never personally had a pre-order knocked back, but I know some who have - but they're usually on very popular items. If they knock back your pre-order you don't get charged, you only get charged after they ship the item to you.

As for prices, they're neither cheap nor expensive. You pay the standard recommended retail price for toys as they are in Japan - so in other words, it's the same price you would pay for Japanese toys if you were to buy them off the shelves from a store in Japan. Then you pay for shipping.

It's a perfectly reasonable pricing policy. The only way to get it cheaper would be either:
+ If you happen to be in Japan you can go sales hunting
+ Get someone you know in Japan to go sales hunting for you
...but sales hunting can be slow and tedious...

There's obviously pros and cons in both ways, but in terms of online shopping I would definitely highly recommend HLJ!