Saw this last night and while it was better than Shrek the Third it still wasn't the greatest movie but had some great laughs and was brill in 3D.
I also bought a new pair of clip on 3D glasses. These are on sale in a few Cineworld branches as a trial for £4 and I think they are well work it.
http://www.cineworld.co.uk/news/212/detail
I found them so much better as I hardly noticed they were there due to being so light and not having to wear a second pair of glasses. They look just like those clip on sunglasses.
They are also selling delux 3D specs at £13, that are styled like aviator glasses and come with a hard case to protect them. A bit costly but they look nice but are only for those not already wearing glasses.