Visited the ruins when in Estonia. The museum is interesting, you have an opportunity to dress in chainmail armour, helmet and hold a sword which is good. Part of the visitor centre / museum is a new build and the views down below to the river are good. There's a stork nesting site on the castle ruins that has been in use each year since the mid 19th century. The castle ruins have been preserved and shored up but there's not too much of it left. The walk down to the river is OK. It is a fairly high part of what is on the whole a very flat country so the views aren't too bad, but there is a viewing tower a short way down the road you can go up for free if it's taking in the landscape is what you're after. It is overall worth going there but feel it is a little over-priced for what it is.

The museum and the ruins outside offer a lot of different activities (most fun for kids, but also for adults). In addition to the traditional exposition in the museum, you can try on the chain armour or medieval clothing (the last one is for additional cost), do some handicraft in a workshop (also extra cost, but not expensive), play in the playroom, admire and shop the handicraft items made by locals, walk in the ruins and climb to one of the towers, have a horse riding just across the road of the castle and if you have more time, take a hike on the hiking trail.
We spent more than 2h inside the museum and would have spent more time outside as well (but it started to rain...). Definitely worth the visit.

Place is nice. If you are near, do the visit. It costs only 1 EUR and you can take some nice pictures.