I think the only major problem with Christianity, as with anything, are those people who take it too far. Most of the Christians I know are really nice, laid back people. I get along with them great. They don't judge, they don't stick their noses where they don't belong, and most importantly, they don't hound people of other religions about either converting or telling them that they're wrong. Which I think other, more hardcore, Christians could learn from. But naturally, the hardcore ones tend to think that the laid back ones are not 'real Christians', as they've told me.
A main problem with Christianity I have is... well, the guys who continually say that every other religion is wrong and that the followers of said religions are blinded fools. Or the ones that actively go around trying to convert (in America, of all places). For the first incident, I can understand why you'd think your own personal religion is correct. That's natural. But the diehards that go out of their way (even if they think it's subtle) to tell others that they're worshipping 'false gods', as arunma has mentioned at least once, well... sorry, man, that's just downright rude, religion or not.
As for converters... no one is going to make me belive in Christianity if preachers knock on my door at seven o'clock in the morning while I'm in the shower. That, in fact, will make me want to be a Satanist, just out of spite. It's the States, Christianity is the biggest religion. People know about it, already. Converting in the States is just irritating. And yes, I know not everyone is well versed in Christian theology (I know a decent amount, despite being an agnostic), but still. If they wanted to gain insight, or convert entirely, they already know where to go.
The religion itself is all right, if anything just for the stories (sidenote: Uriel and Lilith pwn, Apocrypha or not), but my main problem mainly lies with the fundies. Most of the 'regular' Christians are okay. Sorry, Titman.
As for tolerance vs. love.... well, you certainly can't really LOVE someone if you can't tolerate them, at least in my mind. Toleration means putting up with them. You can't love someone unless you're able to put up with their antics.
A second issue is the "Thou Shalt not Kill" commandment, which I'm sure every Christian's heard at least once or twice. Why make it a commandment if god occasionally orders a massacre (at least in the Old Testament)? Perhaps god really is a female, and just has mood swings. Like all those first-born kids in Egypt. It made a point, sure, but most of those kids were innocent. That's not very loving, if you ask me. But the Old Testament reads like a bloodbath, whereas the New is all about love and peace. God must've changed his mind halfway through human civilization to take a more calm approach to things. Or something. And the end of the world. Blow it up instead of trying to save it again, apparently.
Christianity. Lots of interesting stories and legends (although all the REALLY good ones have been dismissed as Apocrypha, sadly), and most followers are nice, but it's the loudmouthed minority that makes it difficult to deal with. Not really my cup of tea, anyway. Too much about servitude and the afterlife. I think people take the Bible too literally, actually. Most of those stories, although based on fact, are probably very exaggerated, like any good legend. And some are probably myths all together, told only to express a moral about the world. Sorry. Never bought into the 'exact word of God' thing.
But that's just coming from an agnostic.