Well, its time to draw some conclusions.
First of all, remember that this firewall costs only about 60$. For this sum of money, it grant you an host of features and quite good performance in the common firewall-only role.
However, if you are tempted to use it as a branch office firewall, you should really give attention to its not-so-stellar VPN performance. If you plan to do heavy use of VPN connections toward your main office, the real discriminator here is the Internet line at branch office: if you have a less then 16 Mb/sec Internet line, the RB750GL VPN performance can be marked as adequate. On the other hand, if your Internet line is significantly faster than 16 Mb/sec, you should carefully consider to get an higher performance firewall / VPN appliance (maybe from Mikrotik itself).
Another limitations is the fact that, while the RouterBOARD 750 GL is capable of deep inspection and layer7 filtering, it has no precompiled attack pattern list, nor any antivirus capability. Especially the latter limitation can be desired on a branch office but, on the other hand, a stand alone antivirus is indispensable in any case.
However, these limitations simply disappear in light of its very low cost and respectable feature list. If you need a home or small office firewall and you don't want to buy a very low profile appliance as the ones that usually come in this price class, look no further than here: the RouterBOARD 750 GL is a very good , capable firewall. The only thing that you must remember is that you need a separate modem / router, as the 750GL has no integrated modem.
Have a nice day!