As much as I love all things Turbob, it's for collectors only; and being the goon that I am, I still want one. As for its library - it's too small and generally not much of a step up from what the plain ol' PCE has to offer. That doesn't mean that it deserves to be bashed, though, as it can still access the entire PCE library; just look at its five (and a half) titles as a bonus.
1941 - great port, awesome tunes, and not available from the competition
Aldynes - excellent shmup with detailed graphics, but it doesn't really look any better than the top tier PCE shooters
Battle Ace - mediocre into-the-screen shmup; slightly prettier than Afterburner II, but still a yawner
Ghouls 'n Ghosts - the best console port of the day (or second to the X68k if you consider that a console)
Granzort - decent action with nice backgrounds and lots of unrewarding exploration
Darius Plus/Alpha - good shootie but only marginally improved when played on the SG