You shouldn't buy any accessory for the Pi (especially one that costs more than three times as much as the board) that isn't on the http://elinux.org/RPi_VerifiedPeripherals
list unless you're willing to be a guinea pig, perform the experiment, update the list if needed, and if it didn't work, get a refund. It's been well-documented that most missing/repeating keystroke problems are due to a power supply and/or power cable with insufficient current capacity at the required 5 volt level. Even if it's marked as being just sufficient (e.g., 700 mA at 5 volts) many of the low-cost supplies' output voltage drops enough to cause problems at full load. I've had no problems with any that can actually deliver the required power, and nothing but trouble with those that are marginal. The alternative is a powered USB hub, which has also been well-documented.
Why people keep insisting on buying any new peripherals for the Pi is beyond me, when there are literally millions of perfectly-usable ones stacked up every year in recycling centers, on corporate loading docks, and most likely even your neighbors' "things-to-go" piles - some have never even been used and are still in factory-sealed packaging, especially in businesses. Thanks to the wasteful marketing hype that typical computing system manufacturers insist on foisting on the public, an ever-expanding volcano of unnecessary material keeps getting pushed into the market just because it makes some business managers' sales sheets look better ("Look how many widgets were shipped - I deserve a bonus!", even though the amount of work they did would be the same for one unit or a billion shipped).
If you don't want to bother checking with a local corporate or public recycling center, in our area we have a mailing list for each community that can be found via Freecycle.org
where people announce equipment they are offering free for the taking, and there is very likely something similar serving your area. If you don't see what you want being offered, expand your search to nearby communities, or you can request particular hardware right down to the model number, and odds are that someone will have something available that's pretty close, if not spot-on.
If you are squeamish about using a keyboard or mouse that someone has sneezed on, not to mention other unmentionable acts, seek out one of the recycled accessories still in factory packaging. Alternatively, the same disinfectants that you probably use to keep the bacterial and viral rabblerousers on your kitchen surfaces down to a dull roar will work just fine (e.g., a tiny drop of dishwashing detergent in a dish of water). Just apply them to clean paper or cloth material and wipe down the accessories without soaking anything. Never spray an electrical device with a liquid directly, and follow up with another water-moistened paper/cloth material to remove the cleanser and dissolved goo, then towel dry. The peripheral will become cleaner than anything the food touches that you consume in your favorite eatery.
It may not be clear from the above responses, but, you should make sure you're using the Raspbian Wheezy version of Debian on the Downloads page that supports hardware floating-point acceleration. It's significantly faster than the earlier Wheezy version of Debian that only supports software-based floating-point computations, even in the web browsers. This may not be intuitive, but, it has to do with how web page elements are scaled, especially text characters and images that make up the vast majority of the information displayed (including extraneous advertising material that often exceeds the volume of the core page info). If you turn off image display in the browser, which allows you to click on an image placeholder if you want to see it, that will also speed up browser response tremendously. Also, try as many browsers as you can as some are faster at displaying certain kinds of info or even whole sites than others, and one may be more appropriate for the content you like to view than another that's faster displaying someone else's material of choice. Also, don't expect to be able to open more than a few browser tabs or windows at once - the Pi is extremely limited in RAM capacity compared with the typical commercial multi-GB systems that have at least ten times as much RAM as the PI ... and not coincidentally cost at least ten times as much.
The Pi was, is, and always will be meant for student educational purposes and, as standard advertising disclaimers state, "intentional inappropriate use is not covered by the warranty". So, expecting the Pi to do any and every computing task you might conjure up is just asking for trouble, especially if you're not capable of analyzing and working around encountered problems. Any web page more complex than a Google search results page generally contains more garbage than information - if you don't believe me, select "View Page Source" on a typical web page and just see if you can find the actual information among the voluminous gobbledygook that spews onto the display. The vast majority of what appears in browsers today is ever-inflating machine-generated formatting and advertising, not the author's intended content. Web page designers and publishers need to study and heed architect Frank Lloyd Wright's dictum - "form follows function", and not the other way around.
Some people aren't going to like this, but, if someone buys an educational product, they should be prepared to learn, and the starting point for learning is to always build on the knowledge those preceding them have acquired. That means actually doing some research, finding and reading the beginners guides and really following the advice for topics on which they're not an expert. If the Pi teaches anyone anything, it should be that "less is more" - less money expended, less power consumed, less marketing hype, less packaging trash, less dependence on corporate bloatware, less acceptance of the status quo, etc.