Although the current state of membership of the House of Lords does appear to be undemocratic in that Peers are appointed, I do think that it's useful to have Lords who have a lot of experience in the professional world and can use their expertise in looking at legislation and contributing to debates. I'd rather have an ex health professional/nurse/doctor talking about health issues than some elected career politician who has had no experience what so ever of the health service but is having a say on bills that will effect the nation.
In recent months it has been apparent that the government have rushed through bills in the House of Commons by limiting the time MPs have to contribute to 2nd readings and report stages. The House of Lords in general spends a lot more time looking at legislation than the Commons does. Every Member of the House of Lords is able to attend the Committee Stage of a bill in a grand committee so they can all provide an input to the amendments, where as in the House of Commons it's a select few who sit on public bill Committees.
Currently there are party and government whips in the Lords but as a rule they won't be bullied in to voting a certain way and are able to vote on their own free will. It is extremely difficult to strip a Life Peer of their title so if a peer votes against party line what exactly are the whips going to do?
If the House was to become elected then the whips would become more effective in a similar way to the whips in the Commons. Elected members would be voting for party line and not for their constituents or own views.
There are only 92 hereditary peers left (75 of which belonging to different parties) and that's only a minor thorn in the side of the House of Lords to remind them that further reform of membership is needed.