Very few bands can claim to have a debut that was in fact their best album, and Blur are no exception. Having said that, it isn't bad at all. There is nothing particularly outstanding to be found, especially if you compare it to their masterpieces from the heyday of Britpop, but I've always liked it.
The best songs are the singles: 'She's So High', 'There's No Other Way' and 'Bang', which are in fact very good, it was pretty obvious with hindsight that Blur would become big. There are other tracks which aren't as good (I'm talking about 'Sing' in particular, which a lot of other fans seem to quite like), they do sound very different to the band that went onto become so popular, but it's distinctive vocals of Damon Albarn which make you instantly realise that you are listening to Blur.
My advice is not to dismiss 'Leisure', there are some catchy tunes to be found, and it was an album full of promise, a real taster of what was to come.