From here. A look at the Algonquian languages in terms of the difficulty they present for the English speaking language learner. Algonquian languages are nightmarishly complicated.
Algic Algonquian
All Algonquian languages have distinctions between animate/inanimate nouns, in addition to having proximate/obviate and direct/inverse distinctions. However, most languages that have proximate/obviate and direct/inverse distinctions are not as difficult as Algonquian. Proximate/obviative is a way of marking the 3rd person in discourse. It distinguishes between an important 3rd person (proximate) and a more peripheral 3rd person (obviative). Animate nouns and possessor nouns tend to be marked proximate while inanimate nouns and possessed nouns tend to be marked obviative. Direct/inverse is a way of marking discourse in terms of saliency, topicality or animacy. Whether one noun ranks higher than another in terms of saliency, topicality or animacy means that that noun ranks higher in terms of person hierarchy. It is used only in transitive clauses. When the subject has a higher ranking than the object, the direct form is used. When the object has a higher ranking than the object, the inverse form is used.
Central Algonquian Cree-Montagnais
Cree is very hard to learn. It are written in a variety of different ways with different alphabets and syllabic systems, complicating matters even further. It is both polysynthetic and has long, short and nasal vowels and aspirated and unaspirated voiceless consonants. Words are divided into metrical feet, the rules for determining stress placement in words are quite complex and there is lots of irregularity. Vowels fall out a lot, or syncopate, within words. Cree adds noun classifiers to the mix, and both nouns and verbs are marked as animate or inanimate. In addition, verbs are marked for transitive and intransitive. Verbs get different affixes depending on whether they occur in main or subordinate clauses. Cree is rated 5, hardest of all.
Ojibwa-Patowatomi
Ojibwa is said to be about as hard to learn as Cree as it is very similar. Ojibwa is rated 5, hardest of all.
Plains Algonquian Cheyenne
Cheyenne is well-known for being a hard Amerindian language to learn. Like many polysynthetic languages, it can have very long words. Náohkêsáa’oné’seómepêhévetsêhésto’anéhe. I truly don’t know Cheyenne very well. However, Cheyenne is quite regular, but it has so many complex rules that it is hard to figure them all out. Cheyenne is rated 5, hardest of all.
Arapahoan
Arapaho lacks phonemic low vowels. The vowel system consists of i, ɨ~,u, ɛ, and ɔ. Each vowel also has a corresponding long version. In addition, there are four diphthongs, ei, ou, oe and ie, several triphthongs, eii, oee, and ouu, as well as extended sequences of vowels such as eee with stress on either the first or the last vowel in the combination. Arapaho words also undergo some very wild sound changes. Arapaho is rated 5, hardest of all. Gros Ventre has a similar phonological system and elaborate sound changes as Arapaho. Gros Ventre is rated 5, hardest of all.