As quite emphatically stated by the other reviews, I really enjoyed this episode. Lore's introduction, a sort of separate twisted alter ego to Data's more rigid nature. By far the best villain in TNG's history makes his way into the show in an amusing, exciting, adventuring way. I think this was probably Wil Wheaton's best episode of the series, with possibly an exception for the episode "Last Mission" which saw him depart for Star Fleet Academy. Lore was vicious, he was truly evil by his own right and he enjoyed kicking the hell out of his more gentle natured brother. Data comes back with a more determined resolve reflecting so much emotion without... showing it really. (Sort of hard to explain). A lot of the particular details had me amused and you really can sit there and just gawk at how big Lore had become.
The episode did reach its flatline though right at the end when they beamed Lore out... exactly where did Wes send him? The Crystaline Entity suddenly stopped its attack, turned its tendrils and ran supposedly because Lore was no longer there, but how would it have known that either?