I would say the basics are extremely easy....I've taken Spanish in school before both beginner and intermediate levels and I've always gotten A's straight A's. For me picking up the basics is easy it's the more complicated stuff that is hard. Wo Ni Ta I learned this quite easy becaue it sounded like Monitor in a way and I was taking classes for health care services back home so you know. The numbers are easier than speaking in spanish too! Now for reading that's a whole other ball game in itself and I have to say that is kind of hard but I'm picking things up. I took a chinese class that was offered as part of the teaching program and I learned that some characters actually look like the thing they are describing. For instance take a look at the character for chicken and you will see that it looks like a chicken it has a head an eye and most  importantly what gives it away is that chicken butt at the end that sticks up like a chicken's does. Water is also easy one of the first one's I learned! So is person it's supposed to be someone walking.

In the beginning it can be quite difficult, but with effort and continual patience you start to see patterns and similarities. I think the hardest part of Chinese is learning the "kou yu" or slang.  It can differ by region or city, and can be hard to master.  But if you interact enough with local business owners (i.e.: Restaurants, repairmen, cleaners, etc.) you'll not only better your language and cultural understanding but you'll make some nice acquaintances and relationships.

The pronunciation itself is not difficult, although the tones can be difficult at first, eventually you will get them. What's difficult is learning to read and write it, because you have to practice enough to train your brain to remember them. Then it takes a long time to learn all the characters. I don't know if Chinese is actually more difficult. I guess I would describe it as taking longer to learn, which can be frustrating as a beginner.

It's definitely among the toughest for English speakers.  

I can compare it to Spanish, even though I'm far from fluent in that.  Spanish grammar is more difficult, and the speed of fluent speakers can be frustrating.  However, Spanish is based off Latin. which has also heavily influenced English.  Can you guess what a "computadora" is?  How about "rapido"?  Do you already have some idea of how to pronounce these words?  Of course you can, because it's similar to English, and, more importantly, it uses an almost identical alphabet (with a few exceptions), which means that if you come across a new word, you can read it.

Chinese, on the other hand, has a simple grammar.  There is no verb conjugation.  Even the pronunciation isn't too difficult after some practice (although I'm still working on it).  The problem lies with the writing, where if you come across a new word, you'll have no idea what it is (native speakers can compare new words to characters they already know and make a good guess, but foreign learners have nothing to relate it to).  Because it has no alphabet, we can't simply read a new word to understand it, we need the pinyin too.  But of course, we can't rely solely on pinyin because there are too many homonyms.