A lot of people on the left have been complaining about the filibuster recently.
The filibuster is an important part of Senate procedure, and always has been, because it prevents "tyranny of the majority" and forces bipartisanship. It means that temporary majorities (and every majority is temporary - if every senator and congressperson were reelected tomorrow, it's likely there'd be a Republican legislature) can't pound through large-scale reforms without incorporating the best ideas of the minority. The Democrats used the filibuster when the Republicans wanted to privatize Social Security, because they were concerned (not altogether unreasonably) that privatizing social security would remove part of the safety net component. (It's a little confusing why Social Security wasn't partially privatized - half privatized, or something - but anyway). The Republicans are using it to try and prevent the Democrats from ramming through unpopular healthcare legislation with absolutely no bipartisanship and no consideration of Republican worries. This is the whole reason the filibuster exists - to prevent one side from forcing its ideas on everyone.
Without the threat of a filibuster, it's likely that abortion and gay marriage would be illegal. It's possible welfare would have been crushed, also. Majority rule has big, big problems. Obviously, unanimity rule is impossible, but some sort of bipartisanship should be required for big legislation, which makes this healthcare bill all the more disgraceful.
Unfortunately, in situations with 60+ senators from one party (like now, after Massachusetts unethically pseudo-gerrymandered their way into having an interim senator), once things pass, it makes it very difficult to repeal anything.
And as an aside, the most comical part of this is that Congress is now going onto a job creation bill. A large number of corporate leaders have already stated that the healthcare bill will make it too expensive for them to hire Americans, and I question whether we can stimulate enough to offset the jobs damage done by the healthcare bill.