A 7 Int does represent a rather slow person. The difference between 10 and 7 may not look big, until you break it down and look at the curve (assuming 3d6 to generate the range of values, ignoring the +2 to a stat). If you look at a population you will come up with the following percent having a specific Int score (any true mathematicians please correct any statistical errors).
Int occurrence/ Percent of Percent of people
Score 216 people population below you
3 1 0.5% 0.0%
4 3 1.4% 0.5%
5 6 2.8% 1.9%
6 10 4.6% 4.6%
7 15 6.9% 9.3%
8 21 9.7% 16.2%
9 25 11.6% 25.9%
10 27 12.5% 37.5%
11 27 12.5% 50.0%
12 25 11.6% 62.5%
13 21 9.7% 74.1%
14 15 6.9% 83.8%
15 10 4.6% 90.7%
16 6 2.8% 95.4%
17 3 1.4% 98.1%
18 1 0.5% 99.5%
So a 7 Int score puts you in the lower 16% or a mid 80s IQ. Based on the following site http://www.iqcomparisonsite.com/IQBasics.aspx (I can make no claims to the accuracy of this site, just one I found) a 7 Int makes you a dullard.
Now that doesn't mean they can not be fun to role play. One of my favorite characters was a lawful neutral half orc fighter with a low int and chr. It was actually a lot of fun playing him as somebody that did not think for themselves, but followed orders like a good soldier. It also allowed a lot of room to grow the character via role playing.
This does not mean you act like an idiot in combat (that is instincts and training imo), but at a 7 Int you should not be doing any creative thinking in the party.
As noted above, I was not a math or stats major...so please point out any mistakes (constructively) that I may have made.
(P.S. Will try to sort out the formatting of the table.)