I'd also recommend going to the next size up (to the 2215), there's quite a big difference in the flow rate. While you can get away with following the manufacturer's ratings for Eheim canisters (German engineers never lie about their work) it's still a good idea to invest in the larger version.
Of course, unless it really is quite a small tank.
You're really only over-filtering your tank if the flow rate is too high, i.e. your fish look like they're in a washing machine. If you intend to heavily plant the tank, a higher flow rate is desirable. It also helps keep the tank clean, as it will pick up detritus from the substrate without you having to vacuum.
Eheims are European style canisters, so they have a lower flow rate (relative to their large media capacity) than many other brands. This has the advantage that you can get a larger canister, and thus more filtration media, onto a smaller tank. (PTs please correct my reasoning if necessary)
As for review (I've got a 2215,2217 and 2213).
-Hugely popular, which means that when something goes wrong (it eventually will) there's a large community who can give you step-by-step advice. In fact, use this forum. I certainly have.
-Simple. Means usually simple to diagnose problem.
-Won't break. EVER. This justifies the high up-front cost, but only if you're planning to do this for a while...
-Media is excellent.
-Instructions are retarded. It's not the language barrier, I read them in German and they're still retarded. (Hint: hook the canister up while EMPTY and then suck on the SPRAY BAR hose for no more than five seconds while all the valves are open).
-Replacement parts are expensive and sometimes difficult to find. (Hint: check eBay international sellers).
-Hoses aren't particularly good quality, they tend to kink if you try and run them over the tank lip without using the proper connector. I use a garden hose for one of mine.
-Remove the fine black filter pad after a week, it just clogs your filter.
One much cheaper alternative is the SUNSUN, white and black canister filter you'll see with any eBay search. The difference in price is so enormous that it may make up for the difference in quality (except perhaps the media). Check out the review on this forum. I know a breeder who has fifty and swears by them.