Hindi is a very dificult language to learn. Even though the spoken language allows a lot of slack, writing it becomes very dificult because many sounds are very close, or the same. With over 35 constanants and 12 vowels, it's tough work.
No it's not. Hindi is supposed to be the best phoenetic language around, as all words are written exactly as they would be said. The 35 consonant and 12 vowel sounds encompass all common sounds (at least in the Indo-European tongue).
If you look in an English dictionary, they use an "extended" form of the Roman alphabet to show how the word is pronounced, because the English alphabet isn't very precise. Yes, there are 4 consonants that represent "d" in Hindi, but those 4 consonant sounds exist in English too, and people use them all the time without even noticing it.
And I can assure you, that no two consonants or vowels in the Hindi alphabet are the same. Whereas, in English, three letters (c, k, and q) are often pronounced the same way.
For English speakers, the hardest languages to learn are the oriental languages, because the writing style and grammar are entirely different from what's common in Indo-European languages.