Slitherine

Are they any good and worth the 48 pts they cost ?

I think so, yes. Being poor isn't so bad when you are on a + or ++ most of the time. Don't let them get isolated and keep better troops on the flanks.
One bonus is that you can get very cheap rear support (if it's available in the army list of course - mob are great for this).

Poor troops are great as long as they have the advantage on the enemy. A fair or losing fight they hate (rerolling 6s loses the fight, then disrupts the unit)

I'd say they are good value as long as:

- you keep them in the middle of the line; they hate being overlapped
- they'll have a POA at impact (avoid impact foot and other pike)
- you're prepared to commit a TC to combat with them if need be

They may not be the best troops for an inexperienced player, as they can come unstuck quickly!

I have had luck with poor troops as offensive spears in 8's. I think the same thought would hold true for the pikes, more is better. I have run my pike blocks in 12's in my last 2 games with mixed results, its nice that the LF can't pelt you with javelins and force a cohesion test unless they are also in big groups (vs Romans they are usually in 4's) They can take more hits with less - modifiers since its harder to get 1HP3B. Down side to it is that they can get hung up.
I engaged 3 cohorts of Romans broke the 2 outer ones and both my pike blocks were stuck as the ends of both blocks were engaged with the last of the Romans. Now that may not be bad but the neighboring cats had broken and that left 2 cohorts to turn and flank charge my line which was lined up all nicely for a burst through etc.
12's are good but they can be a curse as well. I still think when it comes to poor troops there is safety in numbers so give them a try and see how they work for you.

Gotta love those nimble little Romans!

The Pk went into action today in my Med German City list, three blocks of them flanked by some defensive spearmen and some less than mobile warwagons. Supported by 2 units of 6 man unprotected mf xb ( 3pts a base, lovely ! ) they took on the Swiss mercenaries in an Ord. French list.

Mixed results, one failed its don't charge test and rammed some Swiss pike, losing twice, and rolling poorly to rout through another block of pike, some light foot & some medium crossbows too. Luckily the mf & pk rallied from disruption before the Swiss could make it count, and this block valiantly matched the overpaid mercenary dogs hit for hit. The 3rd group lost to some more yodellers, but managed to rally and gave a good account of themselves with a 6v4 overlap always helping.

All in all, much as I would have expected, they did ok, and paying 180 points for 3 supported blocks of 12 is really cheap for a reasonably effective weapon.