"The Treasures of the Tuatha De Danann" is a nice selection of short, and very short, Irish mythological tales and traditions, all recorded (like the rest of Irish literature) in Christian times, but regarding the "People of the Goddess Dana," i.e. the gods of the "pagan" Irish, sometimes involving the traditional heroes of the "Sons of Mil" (or "Milesians" -- a term for the legendary ancestors of the Christian Irish, regarded as originally intruders in the Ireland of the Tuatha De Danann).
The Kindle book is arranged with blocks of Irish (i.e., Gaelic) text followed by their English translation: presumably a hard-copy version would have them on facing pages. The Irish texts are all out-of-copyright nineteenth- and early twentieth-century (well, at least no later than 1930 or so) editions from scholarly journals. The translations are new, and supported by a (very few) notes which directly address the manuscript readings or the meanings of words.
I can't comment on the accuracy of the English rendering, but it is readable, if at time noticeably literal. One can get used to the Irish style rather quickly, especially of the idioms are mostly repeated from tale to tale.
There are a couple of oddities. The most notable is that Morgan Daimler has apparently spent a *lot o*f time with the German-language periodicals in which some of the editions appeared, and hasn't always remember to link up their terms with English equivalents. For example, there are several references to a "von Egerton manuscript," which is simply a half-translated way of saying "*from* (the) Egerton manuscript," that is, a manuscript from a collection then in the British Museum, now assigned to the British Library.
I assume that this is (usually, at least), Egerton 1782, which has a large collection of such material, although there are a couple of other relevant manuscripts (at least) in the collection, which was willed to the British Museum with an endowment which has allowed it to be expanded. (One can now check this on Wikipedia, without which I wouldn't have ventured the manuscript number.)
I've been reading translations of Irish mythological material for decades, and this is a very good presentation of some of the "minor" (i.e., short) tales, some of them quite well-known, at least in outline, and some fairly obscure. I won't go into many details, as they would amount to spoilers, but readers familiar with the subject will likely recognize, e.g., the wooing of a woman seen in a dream by the god Aengus Og (various spellings), and the trick by which Aengus received a home of his own from his father, the god Dagda.
There is also a second volume (for now), "Tales of the Tuatha De Danann," which includes some non-mythological literature, notably the poem "Pangur Ban" (in praise of a white cat), and some incantation and divination texts. I intend to review this one as well, and hope to have more to say (as non-narrative texts don't have a lot of spoilers to worry about).