Overall I would rate it as watchable (just), and probably better than that for anyone who hasn't heard the original Japanese dialogue.
Most of the character voices are OK, but there are some major problems when compared to the original dialogue.
The first is that Kelly Sheridan isn't Maaya Sakamoto. Ms Sheridan is trying, and does a good job all told, but good doesn't cut it when being compared to "Oh My God! How cool was that!"
The second is that the direction of the opening tags is stridently insisting that the events of the previous episode were real instead of the questioning tone around those events possibly being a dream or a vision.
This is additional dialogue and completely changes the tone of the tags, and by extension, the tone of Hitomi in an unfortunate way.
The last major problem in the episodes so far is Dilandau: Axe Crazy is really hard to do well, and this is why Mark Hamill's Joker in the animated Batman gets such high reviews. Andrew Francis comes close but doesn't quite manage it in the end.
However these are the only major criticisms thus far so as I said the dub is watchable but I'm unlikely to do so given the choice.
Day 1 - Fateful Confession / The Tower
Day 2 - The Girl From the Mystic Moon / The Ace of Serpents
Day 3 - The Gallant Swordsman / Death
Day 4 - The Diabolical Adonis / The Hanged Man
Day 5 - The Seal of the Brothers / Judgement
Day 6 - Capitol of Intrigue / Justice
Day 7 - Unexpected Partings
Day 8 - Sub vs Dub
Day 9 - The Day the Angel Flew
Day 10 - Memories of a Feather
Day 11 - The Blue-Eyed Prince
Day 12 - Prophecy of Death
Day 13 - The Secret Door
Day 14 - Red Destiny
Day 15 - ???
Day 16 - Dangerous Wounds
Day 17 - Lost Paradise
Day 18 - The Guided Ones
Day 19 - The Edge of the World
Day 20 - The Gravity of Destiny
Day 21 - Operation Golden Rule of Love
Day 22 - False Vows
Day 23 - ???
Day 24 - Reaction of Fortune
Day 25 - The Black Winged Angel
Day 26 - Storm Premonition
Day 27 - Fateful Decision
Day 28 - Zone of Absolute Fortune
Day 29 - Eternal Love
Day 30 - Looking Back at The Vision of Escaflowne