I can't see any additional rights that I have that I didn't have before it became part of British law. All I see are dis-benefits.
Why is this a good thing? Prisoners are still citizens. Disenfranchising them only serves to further alienate them from society.
Time and again the ECHR has served as an important check on breaches of the European Convention by the UK. But a few examples:
http://en.wikipedia.org/wiki/Smith_and_Grady_v_United_Kingdo...
http://en.wikipedia.org/wiki/Saunders_v_United_Kingdom
http://en.wikipedia.org/wiki/R_v_Bournewood_Community_and_Me...
http://en.wikipedia.org/wiki/Sutherland_v_United_Kingdom
Which human rights do you specifically want to lose?