I like the Martinelli-letters. At first I wasn't sure, but now I do.
He definitely was trying to get laid or at least saw himself in some sort of contest with Pound, courting for attention from his ex-mistress. That's very much there, it springs from every page. But being Bukowski he didn't do it in some dull flat way, he packed a lot of energy and unique creativity into it.
Besides, Jane was still alive then and Bukowski was virtually unknown to everybody. His situation at that time was very different to the following years, it really was the beginning of his career and the life he would become known for. The letters are very different than all the other collections, but that makes them that more interesting to me.
Some of them are really up there with the best of his later collections, imho. For example the one he wrote to Martinelli on his birthday while sitting around and waiting/fearing the arrival of a singing telegram from Jane, which he thinks will be his birthday present. I must have read that one about 14 times and still have to laugh. Tragic, mad, true, hilarious genius, really. Or, in one word: Bukowski ;)