What are the limitations of this telescope?

Celestron Astromaster am 114 EQ reflector telescope.
114mm aperture
1000mm focal length
f/9 focal ratio
20mm and 10mm provided eyepieces
Highest useful magnification 269x
light gathering power 265x
optical tube length 20inches (51cm)

I added all the detail I thought would make a difference. Tell me if you need more information.

I just want to know what I will be able to see with this telescope. Its very cheep so I don't even know if it can do anything
I already have this telescope. It was a gift from a couple years ago. Is there any way to make it preform better?

I would not recommend this scope to anyone.  The fact that the apeture is only 4.5 is just the tip of the iceberg when it comes to reasons NOT to purchase this.

Well, ..., bottom line:  Don't buy that scope & here's why:
1) The 4" aperture is too small to bring out detail in planets or all but the brightest deep sky objects.
2) The mount is a cheaply made equatorial mount.  This is the most difficult mount to setup & use.  Throw in the cheapness factor & you've got a recipe for extreme frustration.
3) The Tube has a short focal length rendering it a very poor scope for deep sky work.
4) The optics are very cheaply made.

See the write-up below for a decent scope to buy.
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When considering a first scope watch the following video on how to select a first time telescope: http://www.mycarolinatoday.com/2010/08/telescope-101/

Also, read the following article: http://www.raleighastro.org/observing/general-articles/102-purchasing-a-telescope

The best pricing for a decent first scope is a Dobsonian scope w/a 6" or 8" mirror from Orion (e.g. Orion XT6 - $279 or XT8 - $329.95).

The two dobsonians I suggested are great visual beginner scopes & are super for just taking into the backyard for casual observing but will definitely hold their own at any amateur astronomy gathering. They are also easy for young people to use and operate.

Dobsonian scopes are durable, of higher quality, and (w/a 6" mirror) you'll be able to see all of the Messier deep sky objects (DSO's) plus many of the brighter NCG DSO's, many stars plus; Mercury, Venus, Earth's Moon, Mars, Jupiter and it's moons, Saturn, its rings & moons, Uranus, Neptune & the dwarf planet Pluto, as well as, many of the minor planets, comets, & asteroids. Additionally, it's easy to transport, setup, & use (under 60 seconds from car to ground ... no kidding).

Bottom Line: any scope with less than a 6" mirror, IMHO, would be a waste of money. See the links below for low priced dobsonian scopes with 6" & 8" mirrors. However, the larger the aperture (size of primary objective ... like an 6", 8", 10", 12" mirror or larger) the better.

For more advice I would suggest that you contact your local astronomy club.  You don't have to own a telescope to join! Joining your local astronomy club is the best way to nurture your passion for astronomy.  Plus, you'll find that they'll be able to provide you lots of great advice and support for acquiring & operating a telescope.

--- Edit ---
To maximize the scope's performance, try the following:

A) Set the scope up during the day in accordance w/the user manual. If necessary watch some YouTube videos on setting it up.  This way you'll know how to set it up w/o fumbling around at night.

B) Align the finder w/the main scope.
    - During daylight hours center the top of a far off light pole in your main scope.
    - Adjust the spotter scope so the cross-hairs are centered on the object (as best as possible) in your main scope.
    - Using you finder scope move the scope to another far off light pole & center the finder scope on the top of the light pole.  
    - Look into your main scope the top of the light pole should be centered in the scope.  If not, repeat the steps above until you can center a far away object with your finder scope & have it appear centered in your main scope. You must get this right else finding deep sky objects will be very difficult.

C) Make sure the scope is collimated.  This will keep objects crisp and clear wen focused.  (Source links 2 & 3 below)

D) Download (free) Stellarium (see source link 1 below). Use it to locate objects you wish to observe before you go out at night.  Two easy objects to find are the Moon & Saturn (in the constellation Virgo near Gamma Virginis).

E) Many deep sky objects are visible to the naked eye but, not all are. You will need to learn how to star hop. "Turn Left at Orion" is a great book for star hopping.  
Use your finder scope to find the general location that you want to look in.  Use your 26mm Plossl (in your focuser) for finding the object with your main scope. Some other easy late spring objects are The Ring Nebula (M57) - Lyra, Dumbell nebula (M27) - Vulpecula, & The Great Cluster (M13) - Hercules. Don't get frustrated if you can't find these objects at first.  I had difficulty when I first started so give yourself some time.

F) The Astronomical League (Source Link 4, 5, & 6 below) has some great challenge programs for beginners.

G) Again, your local astronomy club can be a great source for helping you to learn how to use a scope.  Some clubs like the Raleigh Astronomy Club (www.raleighastro.org) offer free telescope tune-up clinics to help you get your scope up & running in tip-top condition.

--- Source links ---
1) http://www.stellarium.org
2) http://www.schlatter.org/Dad/Astronomy/collimate.htm
3) http://www.skyandtelescope.com/howto/diy/3306876.html
4) http://www.astroleague.org/
5) http://www.astroleague.org/al/obsclubs/lunar/lunar1.html
6) http://www.astroleague.org/al/obsclubs/messier/mess.html