Theoretically speaking...

Music is a very personal, subjective thing. However, as Victor Wooten would say, in practice there is a perfection. The important thing to remember about theory is it's ex post facto. It explains music, but it doesn't define it. Having said that... I personally think theory is the fastest way to get your head wrapped around what's going on in music. This will accelerate your learning process, if used right.

Music is a lot like a language, and if you want to communicate your ideas to people and to yourself, then you need to have some common ground. It's all about what you want to get out of playing the guitar. If you just want to learn a few songs that you like, and you happen to like relatively simple music (from a theory perspective), then not having an understanding of the underlying explanations probably isn't going to hamper your progress very much.

However, if you do learn theory, you'll find that you'll start thinking about the guitar in perhaps a rather different way. Rather than chancing upon patterns, you'll actively be seeking them out. This means that when you learn something you'll remember it better, you'll understand it better, and you'll be able to extrapolate from where you are much better.

Some people have an intuitive understanding of music and how it works, and they don't feel the need to articulate it to themselves or anybody else. I however, am unfortunately, not one of those people. For many years I just "played guitar" and didn't bother with the theory side of things. However, when I did start to get into theory, I saw my playing and understanding of music progress at an exponential rate, compared to when I was just fumbling around in the dark.

The best I advice I can give you is to think carefully about what you want to get out of playing the guitar. If you wish to learn to improvise, or learn "complicated" things, or just have a very broad appreciation of music, then learning theory is a good idea. Heck, even if you don't learning theory is a good idea. I'd personally say it's damn near essential, but lots of people would disagree with that statement (and others, I supposed, would concur).

If you're just playing for fun, then at the end of the day, it's best to decide for yourself whether you think it's worth investing the time and effort in learning theory. I can honestly say that while it may appear difficult at the start, in the same way that learning a language may be difficult, once you have the basics down, everything just sort of starts to come together. I don't think that *learning* theory is ever a bad thing. Letting theory completely dictate what you play... probably not such a great idea. But learning it? Never a bad thing. After all, knowledge is power.