Released in the wake of Alejandro Sanz's collaboration with Shakira, "La Tortura," which was far and away the most popular Latin song of 2005, El Tren de los Momentos is a continuation of the broad stylistic excursions of the Spanish superstar's previous album, the Grammy-winning No Es Lo Mismo.

Sanz seems increasingly comfortable with moving beyond his comfort zone -- that is, fairly generic romantic ballads laden with complex language sung distinctly -- and here he refines the rough edges of No Es Lo Mismo for an album that is smooth while at the same time risky in its refusal to reprise the sturdy balladeering of his past.

Notably, the album is graced with several superstar features, including collaborations with Shakira, Juanes, Alex Gonzalez of Maná, and Residente of Calle 13.

These features are some of the album's several highlights, "Te Lo Agradezco, Pero No" and "La Peleíta" above all.

The lead single, "A la Primera Persona," is another clear-cut standout.

On the surface, it's an odd song, from its immediate opening tension to its concluding avalanche of breathlessness, yet its unconventional structure is a chief aspect of why it's such a memorable and moving song.

In fact, if not for the brief trumpet solo two-thirds of the way through, Sanz rambles on almost violently through the song uninterrupted, not even stopping to catch his breath.

There are numerous stylistic exercises here, namely "El Tren de los Momentos" (funk), "Se Molestan" (rock), "Donde Convergemos" (jazz), and "Te Quiero y Te Temo" (country), which are curious, though not necessarily impressive songs.

Better is "En la Planta de Tus Pies," a beats-and-piano (trip-hop?) ballad reminiscent of Sanz's traditional material, of which there is painfully little on El Tren de los Momentos.

Longtime fans, particularly those fond of his romantic songs, are sure to be frustrated, if not infuriated, by Sanz's apparent refusal to sing the kind of love songs that were long his stock-in-trade.

However, those who are open to new sounds from Sanz will have little to complain about, for El Tren de los Momentos is perhaps his most willfully diverse album yet, and it's one on which it sounds like he's genuinely entertaining himself -- again, not unlike No Es Lo Mismo.