He has a strange tail, assuming that he is a sharklike creature! I dont really think that he needs tail - the fins and the head are making him to look enough like shark… andthe grills idea is good too!
You’re going in the right direction.
Sharks actually do have nostrils, and I do intend to put in gills when I do the normal map. I definitely agree about fixing up the neck - I intend to get around to that eventually.
The tail is based off a bignose shark, and I kind of like it enough to keep it in.
I’ve added places for the toenails to be extruded from, but I think I might have to add more cuts ‘between’ the toes. The toes themselves are meant to be webbed, I just think it adds to the aquatic look.
Attachments
I made some adjustments to the toes so they look more like a normal ones. Still keeping them webbed.
Attachments
I’ve extruded the toenails and add a shot of the face as well as a Cycles render. I’m currently thinking of reworking the face topology so that facial expression will be easier to create.
Attachments
Some minor changes to the torso geometry, as well as a shot of the face with grease pencil drawing showing where I plan on adding new lines. Also a new cycles render.
Attachments
I looked up the words ‘shark tongue’ and got information about the basihyal, a small peace of cartilage on the roof of the mouth. I’m thinking of modeling a tongue that looks like basihyal, only I can’t find a good picture of one.
In the meantime, have some more Cycles renders.
Attachments
I really like this. Have you considered flattening the top of his head to make it more shark-like? His body is quite serious but the head seems a little cartoony. It’s more dolphin than shark. Other than that I think you’re doing a great job.
I’ve thought about the head shape, but I decided to keep it the way it is as land-based predators have forward facing eyes, and this creature is partly a land dweller. I honestly can’t see how the head looks like a dolphin, if you look at a dolphin’s head, it’s completely different.
The position of the eyes above the snout/nose is what I was getting at. I suppose you’re right though it doesn’t look like a dolphin.
Sorry about letting this go so long without updating. I’ve been thinking about the head, specifically how to change the facial structure for a wider range of facial expressions. I don’t want to make any permanent changes yet, so I’m just posting a screenshot of a retopoed mesh.
Attachments
And my internet is back up.
A more complete version, showing what the new face would look like one integrated into the mesh.
Attachments
I’m guessing that the new expressive face is okay, then?
Now this is very interesting, both from a mesh and a biological view. All previous responses were good advice - particularly about the loops and simplifying - but I can still see some un-necessary complexity in areas like the top of the foot, the back/lower torso, etc where faces could be deleted and ‘evened out’, loops made more consistent, etc. Unless you are going for a really high-res model, a lot of the mesh complexity can be achieved through subsurf modifier.
Biologically - and I don’t even know if you want input on this or if it’s completely a fantasy creature - I assume this is either a biped/shark hybrid, or an evolved shark that retains some of it’s ancient morphology. If you haven’t done this already, think about what environment this creature will be living in, and what it needs to succeed in that environment. For example, if FutureShark has retained swimming as his main form of locomotion, then he probably wouldn’t have any toes at all - feet would be wide and flat, for propulsion and occasional standing. Hands would not have five fingers, but two or three - FutureShark doesn’t need dexterity as much as he needs surface area for swimming control, and the ability to grab and hold. Definitely no nails; you could apply thickened, nail-type extrusions which are biologically justified by a development of cartilage to protect the tips of fingers and toes.
If he’s only walking occasionaly, calves would be very skinny - and the entire body would be as streamlined as an otter or sealion, without the superhero chest. I would extend the ventral fins up toward mid-torso for additional swimming control and stability. They are small now and wouldn’t add much to the creatures abilities.
But if this is more of a mutant or total fantasy creation - SharkMan rather than FutureShark - then anything goes, as long as you can justify your creation to its purpose and living conditions. 
Expressive face is looking a little like the Jabberjaw cartoon of the 70’s. No opinion, maybe that’s what you’re going for.
Overall very creative and nice work!
Thank you for taking the time for to help me with this. I’m have another look at it and see if if can get rid of the extra verts.
Biologically speaking, what I’m aiming for is a creature equally capable on land and the sea. The nails are from a suggestion by a previous poster, perhaps I shouldn’t have followed it. As for the feet, I decided to base them off human ones while adding
About for the basic design, such as the positioning the fins and body shape, I agree with you, but at the same time I also I feel like I just need to finish up this character.
Right now my main priority is making sure the facial geometry is suitable for rigging. I’m aiming for a more expressive face.
I’m sorry for not getting back to you sooner, I’ve just been juggling several projects at once.
I’ve taken a look at the the model, and I can’t find where the unnecessary verts are. The geometry looks alright to me.
I may have been referring to something you already addressed. When I first started looking at this post I didn’t realize it went 3 pages!
Thanks anyway. How does the face look?
IMO the face has a cartoonish appearance that I think works, but that might not be what you’re trying to achieve. It looks a little too friendly, maybe teeth will make it more threatening. I think it will be difficult to make an expressive shark that doesn’t look cartoonish. By nature sharks don’t have much expression at all.