I bought the Harrier at the start of this sale and have been having a blast with it. I rarely if ever touch Air to Air in DCS, always mud moving, and I think the Harrier is perfect for me:
The V/STOL capabilities and operating from the Tarawa is unique and challenging.
The built in DMT (targeting sensor thingy) is cool and gives you options if you want to skip a targeting pod for various scenarios.
Unique (for DCS) weapons like the Sidearm anti radiation missile and laser guided Echo maverick. The echo maverick is really interesting to use as a stand off weapon.
High quality 3D meshes and textures.
Other unique features like FLIR overlay on the HUD for night operations (I know it's slightly misaligned due ta bug or otherwise, but it's still cool and useful for target aquisition).
Great fun. And I haven't ran into any showstopper bugs. My other go to aircraft is the Mirage, so I'd say I'm very happy with Razbam overall.
Being a 3rd party developer to DCS is basically operating in a niche within a niche within a niche, and given that development of these modules often take place parallell to another, full time job, I'm very happy with the results.
But as mentioned above, you might still want to check the bug report forum just to see if there is some specific aspect of the aircraft that you plan on using a lot that has issues.
I also recommend Red Kite's videos on the Harrier on YouTube for getting a feel for the systems: