Nabokov can write, yes. I had read Lolita, and have just finished Luzhin's Defense (tr. Michael Scammell). Comparing the two seems both natural and unfair. The prose in Luzhin does not sparkle like that of Lolita; it does not taunt quite so much, and it is less vivid. Is it less good? Hard to say.
In both books, Nabokov occasionally surprises the reader with a thoroughly-unexpected metonymy or a zany choice of simile. In both, he carefully calculates his pace. But in Luzhin, time is unclear, and only one of the principal characters is named; in fact, we don't even know his full name. It feels as though his wife doesn't, either. The soporific autism (or near-autism) of Luzhin is conveyed to an extent by the vague circumstances, which Nabokov manages to maintain despite said freshness of description.
The "show-down" scene between Humbert and Quilty at the end of Lolita was just fabulous. The whole Quilty affair, come to think of it, is exceptionally cunning; I can just picture Nabokov curling his lips wickedly as he came up with the many literary schemes that make up Lolita. I'm pleased at having caught quite a few allusions and having puzzled out several confusing passages; I do, however, confess I resorted to Appel's The Annotated Lolita on occasion, when I just knew I'm missing some pun or reference, reading some setence.
But Lolita is not just about Nabokov's fun and games. It tells, quite engrossingly, the (somewhat unlikely) story of Humbert Humbert, and it made me think about the character of Humbert, a character that offered me a chance to think of "child molester", "sexual pervert", and "pedophile" in terms less monotonous than the real child molesters we read about in the papers (e.g. the now-familiar story: losers, often retarded or otherwise mentally handicapped, unemployed) -- here is an educated, decadent man, a European ("Old-world", as he is fond of saying) academic who tends to quote Ronsard, and he is inseparable from the baseness and unfairness that is the wilful seduction and abuse of a child. But no, wait, she was the original seductress, wasn't she? Is this a way out? Can we absolve poor Humbert? No, we cannot. Nabokov quite skillfully grades the reader's discovery of the scope and force of Humbert's depravity, and on the plain moral level, he is the scum of the earth. Lies, forgery, theft, and even murder are all means for Humbert to achieve his end. Such a man cannot be moral by standards agreed upon by western society.
At the same time, we are reminded that other people can be scum, too: Quilty certainly is, and it is ironic that in his hungover state he appeals to Humbert's basic sense of decency.
I think Nabokov has created a remarkable character in H. H., and though it was a troubling read at times, I have no doubt I shall return to Lolita several times in the future. Speaking of characters, Lolita herself is inscrutable, surprising, and perhaps Nabokov did not want us to identify too much with her. Her mother, Charlotte, on the other hand, is a wonderful character, and her image remains very vividly in my memory today, especially in contrast to the vague character of Luzhin's wife, of whom we know very little (not even her name!) and who does not excite the imagination.
In Luzhin, I found the descriptions of Russian émigré life interesting and vibrant, though I am sure that there are far more classic depictions in Russian literature, of which I am unfortunately almost wholly ignorant. But one is tempted to treat the setting as nearly autobiographical, what with Nabokov living in Berlin himself at the time, in the heart of that same émigré society. I shake off those thoughts, though; Nabokov is too wily for me -- I can't presume to draw lines between his biography and his contrived details.
To wrap up a confused ramble, I acknowledge Nabokov as a great master of prose, and I shall no doubt be reading more of his works.