Optically it is a fine scope. For planetary photography it will work. One drawback, compared with the LX200GPS series, is the lack of an electrical focuser as standard equipment, which makes focusing at high magnification a bit harder (but still possible), since your hand jiggles the scope when you tweak the manual focuser.. One can purchase electrical focusers as an add-on later (JMI makes one).
For deep-sky photography, the LX90 is marginal at best, with one exception: it will serve perfectly well for piggybacking a camera with lenses of up to 135mm, so long as you buy a polar wedge as an accessory. (No wedge is needed for planetary work, with the very short exposures involved.) The LX90 can be forced to do deep-sky photography, whereas the LX200GPS is specifically made with that purpose in mind. The LX200 has stronger fork arms and more precise gears, and is a better deep-sky photography scope. This is especially true of the 10-inch and larger scopes, which have a two-inch unobstructed light path, compared with the 1.5-inch path for the 8-inch scopes (both LX90 and LX200GPS). The more constricted light path leads to more vignetting of deep-sky photos, and it makes 2-inch eyepieces a waste of money on the 8-inch scopes. Still, there is less and less need for 2-inch eyepieces as premium 1.25-inch eyepieces improve each year.
Electronically, the LX90 is OK--it uses the same basic electronics as the ETX-90, which I also own (in addition to my 10-inch LX200GPS). The Autostar requires a lot more scrolling through menus and is therefore slower to use than the Autostar II that comes with the LX200GPS. It will, however, find anything you'll want to see.
The cheapest way to get into planetary photography is to get a webcam and use Registax, a free software program. See the June 2003 issue of Sky&Telescope for details, including specific suggestions on which webcams to use. There's an article starting on page 117. It may no longer be on the news stands, but a trip to your library to photocopy the article will be worthwhile. I have found that Registax is vastly superion to Astrostack, a similar program mentioned in the same article.