I've been using MSR stoves since they were first put on the market. I always carry a parts kit--it consists of a bunch of miscellaneous o rings and other rubber, plus a spare jet, spare pump leather and an all-purpose (stove-specific) tool. Sooner or later, you'll wish you had one or more of these parts at a time when it's horribly inconvenient that you don't.
You need to learn how to clean your jet, and you need to do it regularly or it will clog permanently. You need to learn how to oil your pump leather (takes seconds, and water can be used in a pinch), how to clean the fuel tube (described in a post above), which takes maybe two minutes. After that, you're good for almost anything which can go wrong. Be gentle with the pump, since the plungers tend to break, but know that you can use them even when broken....for years, if not decades.
I will leave the endless debating about the relative merits of other brands for another day. I've been happy with MSR's, and I've used them a lot over the years, but there's no denying that a bit of advance know-how will save you a lot of heartbreak sooner or later in their use.
Hope that helps.