Messed around a bit in the Ancient Forest, wasn't getting very far so I continued with the story for a while. Completed Disc 2 now.
A common problem I noticed in Midgar is that enemies seemed to be very "glass cannon"-y. They can dish out insanely high damage, but they fall with very little damage themself.
Anyway, for the bosses... the Turks were pretty much the best example of the glass cannons. They pack a punch, but fall far too quickly for this to be a worry.
Proud Clod seemed to be the exception to this. He took quite a while to take down, but was practically harmless. Nothing special really.
The fight against Theo, Locke and Venus was a bit easier than their other two were, I think. Again, glass cannons.
Now, Hojo gave me a good run for my money. His first form doesn't appear to attack (except Capsule), but the samples are deadly. But, also vunerable to Sleep. One Bad Breath and you're basically free to buff up your characters, drain back some MP, then very quickly beat Hojo down. Helletic Hojo was another glass cannon - hitting me for around 13000 damage in Sadness, when I only have about 14000 HP. A torrent of 2xCut and Ultima quickly takes care of him though. Now, Lifeform was where things got interesting. It took me a while to realise his counterattack had Dispel, even longer to realise that this even extended to dispelling Resist. His MP Drain was also annoying, until I realised it could be Covered; since Yuffie is a purely physical attacker, I gave her Cover. I also had Counter Attack and Counter-Morph on her to get some counterattack damage in; eventually I let this become my primary method of offense once I realised how efficient it could be (Combo can lead to up to 8 counters). It was only once I got that idea I was able to beat him. Very nice battle.