The guys at CD Freaks have put together a review of Plextor's new portable DVD writer, the PX-608CU. Here's what they had to say:
As the current maximum writing speed on DVD±R/RW/CD-R/RW media for slim-line drives are 8x/8x/24x/24x, the Plextor PX-608CU are up-to-date on these specifications.

Bitsetting on DVD+R DL media is also a welcome inclusion and ensures good playback compatibility with set top DVD players.
If you'd like to read more, CD Freaks' entire review can be found here.