The problem with electrics as someone briefly mentioned earlier is:
1. You must wait to charge batteries in between flights... Even with a quick charger if you don't have several sets you will fly for a few minutes and then sit and wait. With glow motors it is simply fuel and fly. The bad part about glow motors is they are messy and you have to break them in and tune them to get optimal performance and alleviate the possiblity of dead sticks.
2. Initially the cost of electrics is high. Getting a decent speed control motor batteries along with the other electronics for a small electric adds up quick. For a glow plane you can be up and running at the field for around $300 but when you run out of fuel you are done until your next trip to the hobby store.
3. Because electrics are traditionally smaller they are harder to see and orientate especially for the new pilot. With glow aircraft the planes and generally larger and easier to see and pilot. A small plane can be more twitchy and hard to control for dumb thumbs. On the plus side smaller planes seem to be generally more durable because of the weight and can handle rough landings and take offs.

I am sure there are many many more comparisons but you get the idea... If money is an issue for starting out I suggest glow. You will learn more about the hobby in general and save a few bucks too. Most glow planes that are RTF have very user friendly motors and will give you little or no problems. Electrics are nice because they are simply plug in the battery and fly with no fuss and mess.

Good luck and use an instructor if you can with whatever method you choose to use.