I haven't taken any astro photos with my ETX-90. But I just got the adapter to attach my Canon Digital Rebel to the photoport on the back of the telescope. I just need to wait for the clouds to go away. But visually, here's what you can expect from each planet:
Mercury: with a high power eyepiece you can see its phases but you really have to look hard.
Venus: Now is a good time to look. Its phases are very obvious. By the way, get a solar filter for your telescope. On July 8th, Venus will transit the face of the sun for the first time since the 1800s. And England is the perfect place to watch (weather permitting). And your telescope is the perfect tool to observe this. Practice finding the Sun in advance. (After you have your solar filter and have covered the finderscope of course). For liability reasons, it's not included as one of the GOTO items because you can blind youself.
Earth: It makes a great terrestial telescope too because it doesn't invert the image.
Moon: Awesome.
Mars: Usually rather small and hard to see any detail. During August's opposition, Mars showed some surface markings and polar caps. At first glance, it just looked like a red disk with no features, but after staring at it for a minute, your eye begins to see shapes. At first I wondered if I was imagining them, but after staring for another minute it was obvious that they were real. Don't be discouraged that you missed the opposition. Even though this was the best opposition in over 60,000 years, there will be pleanty more in your lifetime that are almost just as good. Here's a computer sketch of what I saw:
Jupiter: Very impressive. Huge. You can see its 4 moons, and under a clear dark sky, you can see the bands in Jupiter's clouds.
Saturn: Very impressive. You can see the rings, the gap in the rings, and it's large moon, Titan.
Uranus: I've heard that you can see it as a disk in scopes this small, but it never looked like anything more than a point of light to me. The only way I could distinguish it from the background stars was by looking the next night and noticing that it had moved.
Nepture: Same as Uranus, but dimmer.
Pluto: not visible.
The most impressive deep sky objects will be the Andromeda galaxy and the Pleadies star cluster.