What can I say? I love big, piloted, stompy robots. And not just piloting them, but also managing a group of them.
Story-wise, not the greatest, but it slots into a relatively inoffensive area and time period within the Inner sphere.
Difficulty-wise, left something to be desired for me. This was especially true in later story missions, where I personally found strategy being pretty much limited to "drop the heaviest 4 'mechs owned and shoot through waves of AI".
Being published by Paradox Interactive, DLC is pretty damn expensive for what you get, even on sale.
But that only got me to around my ~250 hour mark with several playthroughs.

As seems to be the overarching Battletech community's tradition, what was given to us was taken and ran far with. Very far.
I am of course talking about modding. The community's tech wizards have basically tweaked, replaced, removed and added to anything and everything that wasn't bolted down. Personally loving 'mechs for their customisation, I love all of the people who dedicate their time to customising the game about 'mechs, so the 'mechs can be customised.
If ridiculous depth in theory crafting builds is your thing (and you want an extra hard kick of difficulty), there's always the option to crank it to 11 by installing Roguetech, probably the most well known modpack out there. As far as I know, there's also BTA3062, which serves as a decent middle ground between the vanilla experience and the sometimes bone-grinding difficulty of Roguetech (though you could even customise Roguetech to be easier if you wished).

This'll probably be my favourite game for a long time.

Hahaha mechs go brrrrr

Very enjoyable & close to the table top game in terms of game mechanics.