Hello Simon,
As some have mentioned the round back takes some getting used to, and the composite body has a different sound that a wood body. I don't care for them but that is just me I have some friends that swear by them. Ovation is a nice guitar but there are some others you may want to look at as well.
Depending on your budget Taylor is one of the best for sound, quality, and playability. but they will also set you back mega bucks. Takamine guitars are great, and play very nicely, as well as being quite affordable. Martins are nice sounding but to me they don't play as nicely as a Taylor and they too are pricey. Gibson Hummingbird is nice but again expencive. Alverez also makes some very nice yot affordable guitars.
Mainly it depends on two things your budget and what you feel comfortable playing.
My choices would be; Top of the line - Taylor, or Affordable - Takamine.
But if you like the Ovation then that is what you should get, as i said they do make a great guitar. As long as you play it does not mater what you play.