I think it is probably safe to assert that to read Emerson is to be forever indebted to him. His wording, his clearness of thought, his determination, his warmth... He has all the qualities one could ask for in a writer, and all one could ask for in a mentor. Nietzsche held Emerson's books the closest, and said they were above his praise; Borges added "Whitman and Poe have overshadowed Emerson's glory, as inventors, as founders of cults; line by line, they are inferior to him". James, the very Whitman, Proust, Frost, have all also praised him sincerely. Judging from other reviews, the love for Emerson hasn't diminished, more than a century after his passing.
For those who are not familiar with his works, it should be noted that Emerson is, without a doubt, a very unique writer. I was surprised when I realized that there is more poetry in his philosophy than in most verse books, yet he is always lucid; and that his poems, although hued by an impressive depth of thought, remain always passionate. He was renown as a brilliant lecturer, and his essays have all the force and simplicity of the oral form. Few people are so rich in memorable aphorisms, and one finds a treasure of a quote in every sentence: "A drop is a small ocean"; "We are not built like a ship to be tossed, but like a house to stand"; "Whoso be a man, must be a non conformist"; "Punishment is a fruit that unsuspected ripens within the pleasure which concealed it"...
Those looking for a good introduction to Emerson can't do wrong buying this Modern Library Edition. In fact, those who are familiar with Emerson but are looking for an inexpensive paperback to carry around probably should pick this one up too. It includes all his major works; a very generous selection of his lesser writings; 23 poems, and a great introduction by Mary Oliver. I was a little puzzled when I saw that they included very little from Representative Men and kept English Traits in its entirety, instead of the other way round. It then occurred to me that in English Traits one gets a glimpse of the journal-writer, the philosopher, and the poet interwoven all in one. Those looking for a more complete, durable edition of Emerson's works should probably go with the Library of America ed. (2 volumes), or the very expensive and very thorough Centenary ed. (12 volumes!!). You can easily find all his oeuvre on the internet, though, so you don't need to buy book after book just to glean everything he wrote in his lifetime.
To put it simply, if you have any interest in philosophy, literature, poetry, religion, or life, read Emerson. You may not be convinced by his arguments, but there's no point in nodding your way through a book. What remains after you finish reading it is what counts, and few writers can be found whose works are as pervasive and fondly remembered as Emerson's are.