A PA28 is something you sit in, like an airliner. A Robin is an aircraft you wear. At least, that's what it feels to me like. I like them a lot.
As far as the DR400 series (the most common ones) is concerned:
Pro:
- Visibility is excellent, far better than a PA28
- The Robins I fly all have a decent and logically laid out (VFR) instrument panel, to a large extent unmodified from the factory. The PA28s our club owns all have a long and different history, with multiple upgrades during their lifetime, leading to an inconstent layout with knobs, buttons and instruments all over the place.
- The 160 HP or more versions have very decent lifting capacity. But the sub-160 HP versions, including the Mk. 1 135 HP TDI Ecoflyer, are really only 2+2 (2 adults, 2 kids). (I understand the 155 HP Ecoflyer, with the 2.0s engine, is also a good hauler, but I have never flown that one.)
- The versions with the saddle tanks give you 190 liters of fuel capacity - which is bladder bursting endurance. Although take care with the fuel selector. The one we have requires you to set the fuel selector pointer rearwards for the main/center tank, and forward for Off. Not a good design.
- Very benign handling at all speeds including the stall.
- Stick instead of a yoke.
Cons:
- Wings consist of a wooden spar and cloth. This requires that they are stored in a hangar, and the wing surface is relatively vulnerable to people stepping on them, items being dropped on them and so forth.
- The seats not only slide backwards and forwards, but in the most rearward position also tilt backwards a bit. In the most rearward position (the one I use) this gets uncomfortable after two hours.
- When entering/leaving the aircraft, especially if you are going into the back, the natural point to grab is the top of the canopy, but this is not strong enough to support your weight. So be careful to brief your passengers about this.
- Slightly less roomier inside compared to a PA28.
- Only a minority of Robins seem to be equipped to IFR standards, most seem to be VFR or NVFR only. For PA28s this seems to be the other way around.
- The stick gets in the way if you're using large kneeboards.
- The lock mechanism is on top of the fuselage and collects water. For most Robins this means that after a while you cannot lock them anymore with a key due to the rust inside the lock mechanism. This might be relevant on a fly-out of some sort where the aircraft has to spend the night outside at an unsecured field.
- The Robin factory seems to be going through an endless cycle of bankruptcy/acquisition/investment. This means that there are periods where factory support (spares, ADs, SBs, ...) is minimal to nonexistent.
(And I'm leaving now to thrown the Robin R2160 around the sky...
)