I've been to Sharm twice and love the place. That's because I'm a diver though (I did my PADI Open Water there in 2006). If you don't want to dive or snorkel then there isn't much else to do. Not that I've really looked into doing other stuff because my first holiday there was taken up with learning to dive, and my second trip there was just a week chilling out, lazing around and doing nothing in order to recharge my batteries.
I'm looking at possibly going back in the next 12 months for another diving holiday because the Red Sea is unbeatable. It's warm and clear with lots of amazing reefs and fish.
As Tamiyoman says, expect to get a dodgy stomach at some point. Sharm is also known as "Sharm el sh*ts". Just be careful what you eat to minimise disruption to your holiday. By all means take Immodium, but all that does is contain the bug in your body and prolongs the squits. You need to get rid of it as soon as possible and as long as you're not planning on going on loads of trips where quick access to a (decent) toilet may be a problem, it's just best to let your body get rid of it in it's own way. Immodium doesn't always work though, it's probably better to get the Egyptian equivalent if you need it - local medicines for local bugs tend to work better!
I can't recommend learning to dive enough though. I absolutely love it and it's one of the best things I've ever done. If you're not sure, just book a 'try dive' and see how you get on. If you don't like it then stick to snorkelling, you will still see plenty of amazing things even though you're on the surface.
The hotels I stayed at were the
Sheraton which has it's own diving centre attached to it on the beach (Aquarius diving), and the
Sharm Grand Plaza which then resulted in being transferred to the
Hilton Dreams because of the Icelandic volcano eruption. Out of the three, I would probably stay at the Sheraton again. The Grand Plaza was ok, but nothing special, the Hilton was nice but didn't have a dive centre attached to it. The Sheraton was quite posh, was on the beach, had a dive centre and its own jetty for snorkellers/divers.
To sum up, it is a bit of a dump really and focussed on the diving. But it's guaranteed sun and relatively cheap and easy to get to from wherever you are located in the UK.