I ran the three-man instances in Eregion, the School and Library in Tham Mirdain. We had some problems working out the bosses, Elite Masters with friends and/or special abilities, but we made it through them all with a Burglar, Hunter, and Loremaster. We might have fared better with a tank in place of one of the first two.
The instances are compact, taking you in and around a central space. The Moria solo instances are similar. This is a good thing for quick questing.
Each has two or three types of enemy groups, repeated a half-dozen times, plus three boss encounters. Dealing with the groups is an exercise in basic pulling, because all the groups are near each other and/or on patrol. Mix in CC and/or tanking as appropriate for your group. It is not too hard to get one group, and it is not too bad if you get two.
About half the bosses went well, although sometimes with a faceplant because we had no heavy armor (but we did have a rezzer!). The rally circle was not the one at nearby Mirobel, but rather a quick trip back to the doors of the instance (inside). This lets you rush back in and keep going, which could uncharitably be described as zerging it, but I find this valuable given the odds of not having a surviving healer with three people in the instance. No one wants to run back from town every time the cloth-wearing healer hits the floor. Rallying inside also meant that, if you were zerging it, you could get multiple deaths, have massive item wear, and still fail and reset the room. Not bitter.
They are good little instances, both of which you could run comfortably with the same group without devoting an entire evening to it. You get a few deeds and titles, notably “Librarian.” If you want all the slayer deeds, with the associated virtue trait bonuses, you will need to run each about a half-dozen times, as seems to be Turbine’s plan for all instances (based on deed requirements versus enemy counts). Unlike the Angmar instances, you can farm all those enemies without dealing with the bosses, which makes things much easier on your small group.